RTS and FPS games are where the PC is better equipped for the task. Basically anything where a keyboard and mouse cant be replaced with a game controller easily. Also its great for games that already established for online play, something consoles have just recently gotten into.
As far as no real plug and play? What was the last PC you used a 486?
If I could buy an xbox for $200 add a keyboard and mouse plus my 19" monitor and it would play age of kings on the net then I would switch in a hearbeat