I think MANY people would suggest Linux over Windows, and for several reasons. I'll try to give a few examples:
->There are tons of Linux distributions (varied types of Linux OSs) and you can find one specific to your needs or purpose
->A LOT of Linux distros are free
->You're free to do more configuration (of course, you could also more easily screw something up)
->Not run by MicroSoft...
->Linux is, in general, more stable than Windows, and is less likely to crash (I've never had my Knoppix crash on me...)
->There aren't many Linux viruses around (probably not much Spyware either), so you don't have to worry much about that
And of course, the two main reasons NOT to use Linux:
->Not a lot of commercial software is compatible with Linux (some hardware, too), but of course you can usually find a home-brewed substitute that's just as good or even better
->Linux takes a bit more computer-know-how than Windows, and people familiar with Windows might get very confused with Linux at first, because it works a lot differently