My latest build is an AMD 64 bit quad 3.2Ghz. with 4 gb. ram and ATI5870 card. Mobo is Asus M4A79t. Win 7 Premium Home 64 bit OS. Anything I put in this machine runs super fast at max settings....except OFF. If I install OFF and don't tweak too much I'll get 4-5 FPS out of the box. After the compatibility stuff and some dedicated tweaking maybe I'll hit 15 to 20 FPS. My old machine is an AMD quad 2.6 Ghz. with 4 gb. ram, WIN XP 32 bit and ATI 5770 card. I forget what the mobo is. Now here's the thing. I can set up both of my machines side by side and run OFF on both, (I know I only paid for one license but this is in the interest of science so I hope the OFF guys don't get upset.) Anyway, setting both machines identically and restarting until both game environments are the same (ie. sunny day, few clouds) my older, slower XP machine runs at a solid and enjoyable 40 to 50 FPS. The new computer under Win 7 and with the good card struggles at 20-25 FPS. And that's the scoop. Yes, I've installed correctly and yes I've read the FAQ and tried all the tips that made sense. If anyone can help I'd really appreciate it.