I voted PC because:
-you can upgrade it
-there are more games for it
-from what I've heard, Microsoft copied OS whatever from Apple, so Windows 7 has a lot of features similar to Apple's software (not entire sure of this, but it's what I've heard. I can honestly tell you someone if who prefers Apple software trys Windows 7, they will only dislike 7 because it contains the word "Windows" and "Microsoft." It's pretty good).
The only thing I, and I'm sure others, dislike about Windows 7 is that it assumes you have never used a computer before and you don't know anything about computers (this is a bit of an exaggeration). Windows XP gives people who know the nuts and bolts about computers complete freedom in doing their things (like modding, installing certain software, and other stuffs). However, in Windows 7, there are all sorts of warning messages that pop up when you are doing stuff that normal people don't usually do (like modding). Obviously, you can turn off these messages.
I'd recommend you try out what Microsoft and Apple have to offer, everyone has a their own opinion on everything. However, I feel that PC's are the best bet.
E: Sorry, didn't realise how old this thread was!