So, I just built my first "real" gaming PC...and boy is it great! I've got a Q6600 (overclocked at 3.0GHz), 4GB of RAM, and a GTX260 core 216, running on Vista 64-bit. This machine is a beast!
First game I played on it was Crysis, turned everything up to very high and started playing through the game on the hard difficulty (I've already played it through before on my old system)...boy the visuals are great and the framerates were sweet! I also had BFME II and BF2142 on hand and got to try those out, both ran flawlessly with great FPS.
I also recently got Assassin's Creed...the visuals are awesome. I've got everything on max and haven't had any lag or slowdowns. The real thing I was impressed with was the game itself, before I bought it I was talking to a friend who was asking if it would still play well even though it was "made" for the xbox 360/PS3. I assured him it would but wasn't actually sure. To my relief the game plays like a dream and the controls feel natrual.
Case in point: My gaming PC rocks, and I'm looking forward to being able to try out some of the great looking games coming to the PC!