popatim :
It has a 1st gen pcie x16 slot and will indeed take a graphics card.
The best graphics card for a pentium 4 though... is another story. Maybe a 5670 wouldnt be bottlenecked by the cpu.
Do you have a budget?
Yes, don't we all. The answer to your budget question is about $90.00, this is mainly because of the age of the computer, 11 years to be exact. Unfortunately I had to upgrade the O.S. to W7 which requires a better video this is 1 of the many other upgrades needed, like memory which in todays day you need 3 gigs minimum and dual or better quad core processors not mentioning SSD drive with 500ghz minimum. 1 step at a time.