Redjake, 2 things.
#1: you're wrong.
#2: you're rude about being wrong.
the first is totally fine, it happens to everyone. the second is not. So, have some respect.
now, why you're wrong: The Doom 3 "demo" that was leaked, is going to be NOWHERE near as refined, repaired, and pared down as the final will be. in this case, the software you run will likely be MUCH more demanding of your system than the final product, much like many betas. point in case was the WarCraft 3 expantion demo, which had higher system requirements than the final game, purely because all the bugs weren't worked out yet. code starts out ineffitient, and is pared down as development and testing continue. code becomes faster, and less current systems are able to perform better. that's the way these things work.
now, JBX: some frinedly advice: if you can buy hardware today that will run these games fine, why not wait till they come out, so that you can purchase the same hardware, cheaper? this is the broke-college-student approach to hardware upgrades.
hope it helps a tad.