PCI-E or AGP in this situation

[ouaibe]

You should use PCI-E with a fairly cheap 3D card, it will be a very pleasant upgrade indeed. 4650 or 4770 sounds about right and are nicely priced.

[Bond007]

From what I have seen, the dual slot boards (agp and pci-e) only has a pci-e slot that is x4 (as opposed to new x16/x8). For that reason both slots will perform very similarly, so go for whichever card you can get cheaper (likely a low end pci-e). I am guessing by the system specs that they do not game though, so you may want to suggest putting the money towards memory/ processor/ or towards a new system. Also, the motherboard you linked to doesn't specify an agp slot (just pci-e 16).

[Mr. Gruntsworthy]

wind bottlenecks a P4, but that's besides the point...

[Mobile_Crysis]

Definitely go with PCI-e. And to answer the question about the RAM, I have two old computers, one was a Dell with a socket 478 P4 2.8 GHz, and that shipped with DDR1, then there was a Gateway I got a few months later with a 3.0 GHz LGA 775 P4, and that also had DDR1. But later models did ship with DDR2, and they're hard to find now, but there's boards that supported P4's and DDR2 (I know, I upgraded that old gateway) Hope this helps!

[AmuseMe]

I can get a Sapphire 1900GT for $20, that 4650 for $45ish, or I can look at some used 2xxx series.

[Zero82z]

I think the 4650 would still be the way to go. It's fairly cheap, and is good enough that it can be used in a future system should the rest of the components be upgraded.