However, as well as the expected questions on music consumption, iTunes client experience, preferred music genre and digital music player, the survey also asks a series of questions about future PC purchase intentions.

Survey participants are asked if they use iTunes on a Mac or Windows PC, if they have purchased a new computer since starting to use iTunes, and if they plan to purchase a new machine in the next 12 months. If either figure shows a shift towards Mac-buying as a result of iPod ownership or iTunes use, expect to see Apple trumpeting the information in a press release once the survey period finishes in December.

The notion of the 'halo effect' has been much discussed, in part because of the stark contrast between Apple's music player and PC market share. Most estimates suggest that the iPod has around 80% of the global digital music player market, while the Mac accounts for around 5% of the personal computing market.

While the concept is widely accepted as fact among Mac enthusiasts, hard data suggesting its existence is more difficult to come by. In its most recent quarter, Apple trumpeted data suggest that of the million Mac notebooks sold, half were to people who had previously not owned a Mac.

However, with a total of 1.6 million Macs sold in a quarter where Gartner says 59.1 million PCs shipped, there's still a long way to go before Macs seriously eat into the Windows user base.

Another intriguing question in the survey asked: "What is the total size of your hard drive on the computer that you keep your digital music files (or songs) on and approximately how much free space do you have left on your hard drive?"

Apple has typically developed its iPod range by expanding capacity on the disk-based models, but the questions hints that it might be contemplating expansion into additional external storage, or working out if there's enough room left for content to feed forthcoming technologies such as the iTV wireless media centre.
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