silly computer Upgrade question

[Mr. Redundant]

ok heres the system I want to upgrade, my lil bro's system.

CPU: P4 2.6ghz (533mhz FSB)

MOTHERBOARD:ASUS P4PE

VIDEO CARD: ATI radeon 9800 pro (mobo only supports 2x, 4x AGP, but people say theres not much of an increase from 4x-8xAGP)

SOUND CARD:Soundmax (5.1 and EAX support) onboard sound card (mobo)

MEMORY: 512mb DDR (2700)

OS: WinXP

I was just wondering what component I should upgrade that would give the most performance.

he has around $200-$300 to blow on his comp.
thanks in advance, I know silly upgrade questions are asked all the time, however this isnt for HL2.. he is getting into other games that require more power now.

edit: btw I know its a decent system, but he wants to run games in 1280x1024 with 4x AA and 16xAF on and play smoothly.
(he can in some games, but others... theres stutter.)

 

[Mr. Redundant]

Im thinking he needs more RAM, since he already has a damn good Vid card (same as me)
either that or a CPU upgrade?
which would be more beneficial?

 

[RoyaleWithCheese]

I'd go for an extra 512 MB RAM. The cost/benefit of a CPU upgrade is smaller imho

 

[blahblahblah]

RAM and a good set of speakers.

 

[Kerberos]

more ram, definitely more ram

 

[Mr. Redundant]

More ram would really make his FPS smoother?
rather than CPU?

Im looking into getting the Creative GigaWorks™ S750 speaker set for myself 7.1 surround sound...
just need a bigger room now :/

 

[blahblahblah]

If he expects to run a new game at 1280x1024 with 4AA and expect it to run smoothly, you are dead wrong. Heck the new 6800U/X800XT are barely able to do that now. Tell you brother to either drop the resolution or drop the AA.