FEAR was demanding, but had amazing graphics, on my 6800gs I got by with 30-60 fps (usually fps was over 40 and very playable) on 1024x768 res, 2X AA, and basically all the settings on medium & I thought it looked amazing.
Gothic 3 is a new oblivion type of game, I'm going to try the demo soon & its new & demanding so try your 1900 on it.
http://www.fileshack.com/file.x/9806/Gothic+3+Demo
Dark Messiah I believe is source engine based but with some upgrades, oblivion type of game & demanding.
http://www.fileshack.com/file.x/9233/Dark+Messiah+of+Might+&+Magic+Demo
The lowest fps I've ever gotten was in the outdoor level in the call of juarez demo, beautiful & demanding level, your 1900 & core 2 are ridiculously powerful & should laugh at it, but even at 800x600 and low settings my 6800gs & P4 struggled. Wonder how many fps you'd get on this level maxed?
http://www.fileshack.com/file.x/9160/Call+of+Juarez+Demo+-+English
And of course Oblivion is probably the most demanding, the huge outdoor environments are very detailed & demanding on the gpu, even a 7800gtx, top of the line about a year ago can go down below 20 fps when totally maxed at 1280x1024. I hear that having a 512 card is useful for oblivion, and your card is a lot stronger than a 7800gtx. I imagine crysis will give any dx9 card a good workout though.