Well it doesn't look like I will be able to round up the $700 or $800 it takes to build my new system, sooooooo...
I was thinking about pluggin in a "newer" vid card. I have an Asus 6600 in my p4 2.8 ht socket 478, 2gig, system. I usually play CoD UO and want to get CoD4.
I was thinking about a 7600GS or X1650Pro, something in the $70 range. I am not sure about my PSU, but I do have a small 175w psu I could run simultaniously (if that can be done) if the psu wont cut it.
Would any of this even be worth doing to hold me over for another year with my agp system?
well, I've got a similar rig and I've bought a few months ago 7600GT istead of my 9800Pro.
I saw a big difference and I was able to play new games like COD4.
The problem is that some games (like Bioshock) are CPU limited - during the game it run smoothly but loading times were unbearable.
It will be a good upgrade and will keep your system running for some more time but you should consider buying a new rig if you can afford it.
As for the card the 7600GS and 1650Pro (gddr3) will give you about the same boost, you should consider the 7600GT or 2600XT, I know that the prices are very close were I live...
If you're willing to spend money on something as high as a AGP 7600GT card, don't. Not unless you can find one in your price range on eBay. Otherwise this card is a better alternative to the AGP 7600GT:
Just get a P35-DS3L+ E21xx + 3850 + good PSU + 2GB DDR2 RAM
Exactly what I did, except I got a 8800GT and 4 gigs of ram. I got over $100 Rebates coming in as well and it fits very nice with your budget. If you want to save even more money you can stick with the 3850 but know that it doesnt pull near as much horsepower as a 8800GT even the 256MB flavor (Afterall it's just a 8800GT with half the Vram) I picked up a ThermalTake 500W purepower PSU for $25 AR at the Egg. Powers everything great, dead silent, and the 120mm fan exhaust even more hot air out of my case. I picked up a CM centurion case for $15 AR at zipzoomfly. I believe nows a good time to upgrade. Plus when the Q6600 gets dirt cheap you can throw that in the DS3L and OC it to 3Ghz if not more, and be good to go. Oh ya I got a nice CM TX-2 HSF for $8 AR as well. But like I said over $100 of this build is on rebates which is a little annoying.
I would say your best bet would be to stick with the 7600GS or the HD 2600Pro. If your system can handle the plain jane 6600 you've got in there then you should be fine with either card although the 7600GS would be the safer bet with your power supply. The HD 2600Pro is the stronger performer but draws a little bit more power and could stress the limits of your PSU.
Yes, you will see instances of the CPU holding you back. The issue of an AGP 4X slot is very minor and not worth worrying about. I'm sure there is a way to rig up the 185W PSU you have but I really doubt it would be worth the time and effort and possible damage that could be done to your system to warrant it. To top it all off, you may not see a huge increase in performance that you might want. There will be an increase, no doubt, but don't expect anything like double what you have now.
EDIT: Oh, and an X1650Pro uses more power than the HD 2600Pro or 7600GS so I don't recommend it.