Alien vs. Predator runs really slowly on my Windows XP Prof. I have done all the things it said to do in the read me (Defrag Hardrive, lower screen res etc.) but it still runs very slowly. If you know how to correct this problem please tell me.

What pentuium do ya have 'n how much space?

I run a P4 AMD 3500+ Athlon 64, 2.2 GHz, 1 GIG ram, 250 MB HD (half full), 512MB nVidia GeForce 8500 GT on XP Pro SP2. Latest drivers, defragged, everything recommended for fixing problems. 100 times more powerfull than the original PC (P3 600, Win98SE, 64MB video card) that this game ran flawlessly on. The gameplay now is too choppy to run. Changes in screen resolution, compatibility, lower/higher settings - nothing cures the lag.
On my GeForce 6600 I had the same problem as mentioned elsewhere here (HUD on a black screen). On the PC's integrated graphics (ATI radeon) it's same as with the GeForce 8500 - too choppy to play.