Personally I think it will look fine. I play a whole lot of games - FPS, RTS, RPG - games like Far Cry, Half Life 2, Doom 3, UT 2004, Dungeon Siege, Act of War, Wacraft 3, HOMMIV and a whole host of others on my 2001FP (native 1600x1200) at all sorts of resolutions (mainly 1280x1024 or simliar) and it always looks really good.
It's only in 2D desktop work that I find running anything other than the native res looks horrible. I have a 2001FP (native 1600x1200), 1905 (native 1280x1024) and an LG 17inch (native 1280x1024) plus have worked with heaps of different monitors at work and can say that in the most part for 2D you want to run your LCD/TFT at native but for games pretty much any resolution the LCD/TFT can support will look fine.
The only exception to the games was Starcraft on my 2001FP which looked really blocky (I think it was trying to run at 640x480 or something) so really low res on high res LCD/TFT probably looks not so good.