something everyone is forgetting, what can you not do on xbox360/ps3 games? dual/tri screen!
plus a hdtv can only do 1080p (1920x1080) atm but a pc even my silly little 9800gtx can do 1960x1200 or 1200p while newer cards can do 2560x1600 or 1600p, the reason ps3 and xbox360 games are limited to 1080 and some not even that is because tv's have bigger pixels than pc monitors so its difficult to get the picture to look right when they put it on the tv for example for a full hd 1080p tv you need over 32" but for full hd on a pc monitor you only need a 24" screen and thats why pc games usualy have better quality.
oh and if you are rich enough for nvidia 2 gtx460's and 3 identical 3d screens you can also put ANY game in 3D (3d is just a gimmick but still pc has it)