Rock band The Who are to team up with McFly to record a version of their legendary 1965 hit My Generation to launch HMV's digital download site.
The Who will record the track with McFly on Sunday
The high street music chain, which launches its site on Monday, will be up against rival Virgin which launches its own download service on Friday.
More than 10 million songs were legally downloaded from the internet in the UK during the first half of 2005.
Digital downloads made up 5% of global music sales in that time.
However the popularity of portable music players such as the iPod has led to a boom in online services.
Just a handful of legitimate online music stores were in existence two years ago - now there are about 300 different services up and running, including Napster and Apple's iTunes.
HMV Digital will provide customers with a choice of paid-for downloads or a monthly subscription service.
The company will also create HMV Digital sections in its 200 stores around the UK to offer help to would-be downloaders.
Legal downloads surged in the first half of 2005
"One of the wonderful things about music is the way it spans all generations to bring fans together, whatever their age and background," said Mark Bennett, HMV head of digital.
"My Generation is, without doubt, an all-time classic... I can't think of a better iconic anthem for HMV's new download service as it reaches out to existing fans and a new generation of music buyers alike."
Virgin Digital users will also be able to choose from either a pay-as-you-go service or a monthly subscription, costing under £10 per month.
Users will be able to sample songs before they buy from a catalogue of one million tracks.
Sir Richard Branson will virtually launch the service at Virgin's flagship store in London on Friday via a 3D hologram of himself - despite being thousands of miles away on his private Caribbean island, Necker.
He said: "Seeing as Virgin is going digital, I thought I'd do the same."