Bought Halo 2 for PC yesterday meaning that I am now back on LIVE using some of the old 1 month Gold cards I still had from my 360. Halo 2 basically Halo 3 with a different campaign. Graphics are near idential which shows perhaps how disappointing Halo 3's visuals were although Halo 2 has been updated a bit. Multiplayer is still awesome, way more maps than Halo 3 and they are more varied. LIVE works great on PC.
Also got Mass Effect on PC which again is so much better than it was on 360. Better graphics even though no pop in or awful framerate issues. Better controls, better menus etc.
Very pleased with my new PC and that I got rid of 360 because all the 360 exclusives I miss out on will make their way to PC eventually as these games and others have shown. Next up on my shopping list is Gears of War PC.
By the way to afford Mass Effect I traded in Dark Messiah on PC, GT5 Prologue on PS3 cos it was taking up almost 7 GB on my hard drive and I never played it and also traded in FIFA 08 on PS3 because new footie games out in September and the value of it will drop to about £1 soon so I thought to get shot of it now while it still has value.