#6, ur rig is plenty. On my old rig which was a AMD Athlon 1.5ghz, 512mb SDRAM, GF4 Ti 4400 128mb, I was able to run the alpha just about flawlessly and it wasn't even optomized. I even ran it on my Geforce 2 before I got my Geforce 4 at the time.(I don't recommend that :D) My current rig is perfect for it with my GF4ti4400 still in though ordered a GFFX 5900 which should come by Friday. Don't worry, you'll be fine. Cheers!
"This my finest sword. If in your journey you should encounter God, God will be cut." -Hattori Hanzo ~Kill Bill