Give me a good reason why someone who is your average-basic home computer user...should buy a new computer to replace one that is working fine, just to go from XP to Win7.
[crickets]
Why I run Linux
Unfortunately most won't try Linux, they've either never heard of it, heard and believe all the Microsoft negative propaganda about it or a simply afraid to try something "new and unfamiliar".
I started using Ubuntu alongside Win7 and can tell you since I started using it, I spend much more time with Ubuntu than I do Win7.
I run Mint on one of my machines, simply because I think it's the most user friendly Linux distro available, I don't "tinker" in terminal.