If I may make a suggestion... Don't buy anything NIB (new in the box) for AGP as you'll probably get raped unless you're getting some kind of crazy close-out deal..
For some reason, retailers think they can sell obsolete hard-ware at a premium.......?
Sounds like you have an XPS Generation 2...
Things I'm noticing right off the bat: how is your RAM set-up? You have dual-channel capability.. With 1.5 gigs, you may not be taking
advantage of that.. It's best to have stuff in matched pairs.. The ideal set up for you would be to have 2X1gig of PC4000 (DDR 500).
You can find this type of performance RAM in many different flavors for pretty cheap.. Saw some of those Crucial Ballistix 2x1gig sales
for around $50.00. You can probably find cheaper.. I think you're pretty maxed out processor-wise.. You'd get better results from
overclocking (if you can) than you would with another processor (depending on whether you have socket 478 or 775).
As for Video Cards: what ever you do, don't listen to Krusty
Nvidia as well as ATI have several viable choices...
Nvidia offers the 7950GT but it's frequently problematic and I wouldn't touch it with a 10ft pole.
After that, there's the 7800GT, 7800GS.
The 7600GT, 6800GT or 6800 GS are all acceptable but won't touch the performance of a the higher-end 7 series cards.
Case in point, I play with a 6800Ultra AGP on my garage system. I run everything maxed out with 8xAA at 1680x1050.
I keep V-sync on and it stays at a constant 59fps. Never dips...
As far as ATI is concerned, I think the HD3850 w/512 is actually the fastest AGP video card available..
You can find these for under $100.00 and I think this should be the card you get as it will
absolutely outperform anything Nvidia has to offer in the AGP realm..
Without a doubt, this should be your choice for video card based on cost, performance and logic.
Live long and prosper