Doom 3 Running Slow

Hey you guys! Since you've already helped a lot of people with the same problem, I am sure you'll crack my case.

This is the deal: I bought Doom 3 four weeks ago and it is running really slow on my computer, which was bought on the same day.

Here goes my computer's description: pentium IV 2.8 GHz, 512 RAM, windows XP home, video card ATI Radeon IGP 345M (chip type RS200M AGP 0x4337) with a 64mg memory and there still is a load of drive space available.

I am running the game with the least graphic features possible.

So, what is the problem here? I think it's the video card, but would it be the driver? Should I just update it? Or is the video card itself too slow for Doom 3? I even forgot to tell you guys that I'm working on a lap top, so I don't know if changing the video card would be possible. Still, I would like to know if the video card is the actual problem, so that when I get back home from this six months exchange program, I will be able to know what to do with my home computer.

Thanx in advance.

 

It's your video card.