Umm... if you're pc-literate and have a decent gaming system, you probably don't need xbox. all console systems in general caters to people who don't want to spend money buying/building a game rig. If you have a good PC that can play the latest games decently, you probably don't need an xbox. Of course if you're in love with the games for said systems (Halo 2 for Xbox, GT4 for PS2), then you've got no choice but go console. I also find that PC's just LACK certain types of games that are abundant in consoles. For instance, FF style RPGs (any Squaresoft game, Breath of Fire just to name a few) are virtually absent on PC's for some reason. The latter system only has D&D style (Baldur's Gate, Temple of Elemental Evil) and Diablo-esque games. While the D&D games have awesome gameplay in their own right, there's something in the simplicity and the complex storyline of the FF style RPGs that's utterly addictive. Consoles also have a MUCH bigger following as far as racing and fighting games (mainly due to the controller). Xbox specifically has a lot of racing, fps, and action/adventure games. if you're looking for RPG's, it doesn't have much at all (I can only think of Morrowind and Fable).
Personally, I have a PC and am very happy with the games I can play (FPS, RTS). When I do get the frequent itch to play console style RPG's, I whip out the old SNES and PSX emulators and hook up my cheap controller. SNES and PS1 have the best RPGs EVER. I do have an Xbox, Gamecube and Dreamcast but I don't play them that much nowadays... although I really love the Dreamcast.