Microsoft Windows Vista and Office 2007 are available to consumers worldwide.
In a series of posts throughout the day, BBC News technology reporter Andrew Gruen gives his first impressions of the new operating system.
1400 GMT WEDNESDAY
A reader wrote in to tell me he was running Windows Live Messenger on his Vista machine without issue.
So I booted our Vista laptop back up and did a repair install of Messenger. After relaunching the application, it asked to install a new version of Flash, which I did (who knew that Messenger used flash?). I launched it again and was presented with my buddy list. Windows Vista and Windows Live Messenger; together at last for this BBC reporter.
1800 GMT TUESDAY
To round out the day, I downloaded all my favourite free applications from the web to see if they were Vista compatible. To my pleasant surprise all but one worked marvellously.
Windows Live Messenger failed to work
Trillian 3, AIM 5 and 6, Yahoo Messenger, Skype, Google Talk, BitTorrent, Firefox, Netscape, iTunes, Real Player, and even GIMP work well.
Some, like AIM, look a bit out of place and antiquated when surrounded by Aero'ed applications, but they work just as expected.
So what's the lone, non-compliant download? Microsoft's own Windows Live Messenger. Mr Right Hand, meet Ms Left.
1700 GMT TUESDAY
Security warnings are frequent on Vista
Though I'm generally in favour of as much computer security as possible, Bill Gates' "most secure operating system ever" might actually go too far for those who are already security savvy.
When I first started with Vista, I followed the security practices I learned in my Linux days: set up an administrative account, but use the computer for everyday activities on a limited one.
Unfortunately, Vista takes "limited" a bit too literally. If you're using such an account, get ready to be inundated with the yellow security warning windows like the one pictured.
Using an administrative account alleviates most of these problems.
Another side effect of Vista's enhanced security is that it asks for authentication to change just about any setting, install any program or download any updates.
Although it sounds like this would be just as obnoxious as the yellow security warnings, it's not.
Instead, I find it comforting to know that applications can't be installed nor settings changed without my explicit permission.
Vista also tightly integrates the Windows Update service, a spyware removal tool that scans for "unwanted software" in real time, a firewall that's enabled by default (finally!), full drive encryption, and parental controls.
1600 GMT TUESDAY
Networking has been improved under Vista
Once the sole province of the super-nerds among us, networking has now found its way into the home with the proliferation of broadband and wi-fi. Microsoft's last major update to Windows XP, SP2, made networking easier, but it has been improved again in Vista.
Hovering over the networking icon in the system tray shows whether any wi-fi is in range and clicking on it presents an option to connect. A double click on my network and I'm online.
However, for those new to networking the most useful feature is the network map in the Network and Sharing Centre.
Diagnosing network issues often requires an idea of where the problem lies.
This visual representation of a home network lets me see the path information takes to get from my PC to the internet and precisely where problems occur.
1500 GMT TUESDAY
Digital media plays a big role in my life and Vista aims to make using it easier, but does it succeed? Sort of.
Vista aims to make photo management easier
Microsoft updated pre-existing media applications and added some new ones to Vista, but for people like me who already use applications to manage their music and photos and edit digital video, they may not get much use.
The Windows Photo Gallery application is reminiscent of almost every other photo manager I've ever used.
It features a source list on the left and the photos themselves on the right and has a small set of photo correction tools that perform the most basic tweaks including colour correction, red-eye reduction, and cropping. For people who've never used an application like it before, though, it should prove useful.
Windows Movie Maker has been updated to fit the Vista look, but it still seems underwhelming when compared to offerings from other companies. The transitions and titles still look amateurish and working with media inside the movie (adjusting the volume of a sound track, for example) took me far too long to figure out.
Media Centre, however, is a welcome addition to the standard Vista package. Formerly relegated to its own edition, Media Centre is a "10-foot interface" (it can be used without a keyboard and mouse if the PC has a remote control) to all the music, photos and video stored on the computer. Since I have a PC in the bedroom, Media Centre should be extremely useful for watching TV programmes or listening to music before bed.
1200GMT TUESDAY 30 JANUARY
Getting started with Vista is a bit disconcerting. At first blush I felt right at home with a Start menu, task bar and Recycle Bin, but as soon as I started working I found things just slightly out of place.
"Flip 3D" allows for faster access to windows by clicking on them
The Run option has been removed from the Start menu (but entering commands into the search bar that now inhabits Run's old real estate works) and My Computer, is now just Computer.
Then there's Aero - the shiny, glass-like, transparent new visual style. It's a refreshing change from Windows XP's Fisher-Price-like interface and looks great on newer high-gloss LCD displays like the one I'm using.
There is also a spate of new visual effects ranging from Flip 3D which shows all the open windows (pictured) to the zooming window minimization animation. I'm a particular fan of Flip 3D because unlike the window switcher in old versions of windows which only let you page through windows sequentially, it lets me grab a window from far in the background just by clicking on it.
It takes a bit of time to re-learn where common features are on the ribbon
Using Office 2007 takes a period of adjustment. Gone are venerable menus like File and Edit; they've been replaced with a new menu system called the ribbon.
It makes many more functions available with fewer clicks, but it took me a few minutes of hunt-and-peck to re-learn where things are. Additionally, almost all functions are accessible by hitting Alt followed by a series of other letters and numbers - a very nice feature for the keyboard inclined like myself.
The default Office font is also new. It has changed from the serifed Times New Roman to the sans serif Calibri.
Next I'll take a look at Vista's search features.
1110GMT TUESDAY 30 JANUARY
I'm using the search feature a lot. It's superb. As a Mac user, I've been using system-wide search for quite some time and have grown increasingly dependent on it. Vista doesn't leave me wanting for features.
The search box does so much more than search
First, it searches within documents and other application data files meaning, for example, I can type an Outlook contact's name into the Start menu and hover the mouse over it to see their email address and phone number -- very handy for quick calls.
Second, I've saved a search to the desktop that collects up all my music files and "stacks" them up by artist. These saved searches can be dynamically reshuffled based on file attributes called metadata, or data about data.
But the best feature of search is a non-advertised feature: application launching. By hitting the Windows key, typing "word" and hitting return, I can pull up a blank document. Same goes for any application on my machine. This is a very fast way to launch programs.
Goodbye "All Programs" list, I won't miss you.
0950 GMT TUESDAY 30 JANUARY
In the interests of full disclosure I'll admit it: I'm a Mac OS X user at home. I've always appreciated Windows and Linux but ended up using the Mac for my daily tasks.
Booting into Windows Vista feels more friendly from the outset
And, strangely enough, that's why I'm excited to give Vista a try. Five years on from Windows XP, there are a host of new features that have been integrated into Mac OS X for some time or were difficult to use in Linux. Now they're enhanced and built in.
But before I can report back, I've got to go and try it out. First on the docket: the new Windows and Office interfaces.