Microsoft launched Windows 7 earlier in the week
Microsoft has said it is "pleased" with the "strong consumer demand" for its new Windows 7 operating system.
The new operating system was rolled out worldwide on 22 October.
Windows 7 was not included in its results from July to September, for which it reported net profits of $3.57bn (£2.18bn), down 18% from 2008.
Microsoft blamed its 14% fall in revenue on its policy of promising free Windows upgrades to people who bought new PCs during the summer.
The computers came with Vista installed on them, but customers were told they would receive upgrades to Windows 7 when the new system was launched.
Microsoft deferred the revenue from the sales of those Vista systems. If it had not done so, revenue would only have declined by 4%.
The results were still better than had been expected.
Microsoft said reducing costs had helped it to cope with "tough overall economic conditions".