If you like geeky things like magic and dragons, you should really play Oblivion. It's my favourite Xbox 360 game so far (yes I have played Gears of War and Bioshock) and it's about to get even better.
The updates and expansions have been available for a while now via the Marketplace (and as expansion discs on PC) but I've held off because of rumours of THIS bad boy coming. It's basically a re-release but with all the expansion stuff included.
I'll be buying it again because I love it that much. My game clock says fifty hours, but that doesn't include things I've done and not saved and the times I've started new quests to try out different characters. I estimate I've played it for about sixty-five hours and I still discover new things each time I pick up the pad.
Seriously, this is worth your forty quid. Even if you only get the original release (maybe buy my copy?) please, please play this game.
The Elder Scrolls IV: Oblivion Game of the Year Edition is released on 14/09/07 on Xbox 360 and PC. A PS3 version is planned, although it doesn't seem to be on play.com. Hmmm.