You also do not mention your OS.
Some suggestions:
Crysis + Warhead - Graphically intensive FPSes (Yes, I mentioned this because you are already playing Crysis)
Dawn of War 2 - If you have a 64-bit OS, you'll enjoy the Ultra graphics setting and it's a really well polished looking game. It is also a good RTS for both SP and MP.
Hellgate:London - Ok, everyone will say that overall it is a poor game and it's failure highlights this BUT it's implementation of DX10 is the best in any game I have seen or heard of. In certain areas in DX10 1920x1080, all ultra/highest... it looks stunning and pushed my 512mb 4870 to its limits. Should be at an absolute bargain bin price.
Age of Conan - MMORPG. I would research this one heavily before purchase. When I played, it was buggy, unbalanced and lacked content but graphically it is probably the most impressive MMO out there.
Homeworld/Homeworld2/Nexus: The Jupiter Incident/Freelancer/ Freespace 2 (with open source graphical enhancements) - More old school type games but depending on your previous PC, you may not have been able to crank the eye candy to maximum. Barring Freelancer which was merely good, the games above are some of the greatest ever produced and would be a worthy addition to any PC gamers collection.
X3: Reunion - Space-based sim heavily based around space trade and building you own space empire/fleet. Graphically impressive but not everyones cup of tea game-wise.
G.R.I.D. - Very good racing game, looks good to boot.
Unfortunately most of my suggestions are for older games. I cannot seem to find modern games to pull me in and keep me entertained.