I use Ubuntu a lot. I have it dual-booted with Windows XP (You don't have to dedicate a PC to just one OS, you can use more than one and choose which one you want to boot with GRUB, to change OS just reboot PC). It's better than Windows for Web browsing, office, and general PC use (more secure, better desktop effects especially with Compiz) but sometimes not so good with games. I've played quite a few games in Wine just fine (Jedi Academy, Quake 3, SimCity 2000, and others) and also some free games like OpenArena work great in Linux.