Actually, most of the programs that people normally use on a PC are also for Mac. And there are a lot of games coming out now too, check out
www.apple.com/games or
www.insidemacgames.com. If you can, I would wait for the PBs with the Intel processor in 2006 or 2007. IBM has not been able to make a G5 chip for the PB, and with the G4 in it you dont get that much value for your money as you used to. But I guess if you need it now, so theres not much to do with that. You could get an iBook, new models should come out soon, or get a used PB for now. I would def. buy an Apple though, PCs are no good in my opinion. OSX 10.4 Tiger is just lightyears ahead of XP.
http://www.macrumors.com/buyersguide/