It will definitely be open season on Doom 3 -- I would play CS: Source with you all but I don't have Condition Zero. I'll just wait for HL2.
I'll be installing a ton of games. UT2004, BF: Vietnam, Far Cry, and heck, I may even give Planetside another shot. And I'll install the Rome Total War Demo again on the AW. If you haven't played it yet -- download it now! I have a thread on it in the gaming section. If I had to choose between that or HL2, I would have to go for R:TW. But, I'll be buying both anyways most likely .... my wallet will be empty though.