Look, you should get about 40 fps in Crysis with settings on high at 1280x1024.http://www.tweaktown.com/articles/1234/18/page_18_benchmarks_crysis/index.html
On Vista, with "very high", at 1440x900, you will still get over 30fps, I think.
If this PC can play Crysis like that, you can bet it plays anything well. It's a very good PC. Stop worrying now...