-Medal of Honor Limited Edition (that MoH game that came out in 2010)
-FO3 and FO:NV
-Dragon Age: Origins
-Crysis
-Oblivion
-Morrowind with max settings using MGE
I know that none of these games are the most gaphics-intensive, though. Does anyone know of a game that can test my system's graphics cards to the max?
Crysis and Metro 2033 are supposed to be among the most demanding on your GPU. I haven't tried either but I'm able to get at least 40-60 fps for most recent games (including New Vegas, Civ5, DAO, ME2, RE5, Arcania, The Witcher) at 1920x1080, all detail settings maxed, on my laptop which has a much lower class graphics card (the mobility HD 5830, based on the desktop 5770) than the desktop 6850 or 4870 cards. I get constant 60fps on vanilla Oblivion if vsync is enabled, a bit lower with OBGEv2, ENBSeries, QTP3 and lots of other mods installed.
I would be surprised if anyone has difficulty getting decent frame rates on Skyrim at 1080p resolution with any of the first or second-tier AMD or nVidia gaming-oriented desktop graphics cards, especially those of you who are running dual cards. In any case, if Skyrim is the primary reason you are considering an upgrade it would be best to wait until a bit closer to the release date.