OK. I have found a bit of a problem.
According to Gateway's specifications for the 5200 series says that it doesn't have a graphics slot at all.
According to Gateway's specs for the motherboard that came with the 3.2 P4, it has a PCI-E slot.
I guess you're gonna have to open up your case and check it.
Both sources say that your comp uses PC400 RAM, up to 4 gig in 4 slots.