Hey, just read the hardocp article:
"For those of you that think you are not going to have the hardware that you need to play DOOM 3, the fact of the matter is that many of you will be just fine, although an upgrade may still be in your future. As of this afternoon we were playing DOOM 3 on a 1.5GHz Pentium 4 box with a GeForce 4 MX440 video card and having a surprisingly good gaming experience. Even a subtle jump to an AMD 2500+ with a GeForce 3 video card that is two years old will deliver a solid gaming experience that will let you enjoy the game the way id Software designed it to be. That fact alone should let many of you know that you will not be left behind in experiencing DOOM 3."
Your listed system is a monster compared to what they were playing it on. I wouldnt sweat it.
Just my $.02