WinXP is the major competitor for Win7 (and upcoming Win8).

Microsoft earns little from WinXP now.

But Microsoft must keep WinXP going otherwise people with older hardware will be using Linux (distributions) which is proven to work a lot better than WinXP and Linux is much more virus resistant than WinXP, too.

This is why Microsoft keep WinXP going -- MS don't want to lose (some 50% of) WinX customers.

After Win8 debut, they may drop the price of Win7 to get WinXP users to move on to Win7.

I have used Linux for more than 7 years. I don't miss WinX and anti-virus programs at all.

I have learned to use computers and understood how things work -- not blindfolded by Microsoft.

If you want to see what Linux can do -- try one of these popular distros: Linux Mint or Linux Ubuntu. ;-)