Anodizer seems to think the last good Nvidia card was the 6800.
The 7900 GS AGP card is a good card. Is it a 9800? No. It smokes a 6800 Ultra easily enough. More than enough power for anything AH will throw at you.
Even though the HD 4650 card is indeed a more recent card, the 7900 GS is only a little slower, and surpasses it in a few areas (256 bit memory means it has about 3x the memory bandwidth as the HD 4650, pixel fill rate is nearly double, and overall it's a high-end gaming card, where the 4650 is a mid-range card)
For example:
http://www.gpureview.com/show_cards.php?card1=510&card2=611
Question is, are you going to be running games like Crysis, FEAR, HL2, etc?
EDIT: In the link I posted, that's a 600mhz GPU on teh 4650, seems the links Anodizer provided are for 750Mhz GPUs, just FYI.
EDIT2: I'm not saying the 7900 is without flaws, but as a solution to your AGP problem it'll do nicely, and is probably cheap now (if you can find one)
Krust-Sack<-------Providing the AH community (and lord knows who else) bad information on just about any subject since 2003...

You should stick to skinning, bro...
Trap, Krusty is not a good person to get advice from.... Many on this forum will vouch for that... He has proven time and time again that a microscopic
amount if knowledge can be construed into a dangerous thing.. He's never owned any of the hardware he endorses except for the 7600GS which he tried to
pass off as a L33T card and made grandiose claims on what his particular 7600GS could do.. The 7600GS was a budget card that could've been had for about 60 bucks
when it was released.. My best advice: don't listen to Krusty, as many others will tell you..
The 7900 series is riddled with problems.. They are WELL known for running hot.. If you don't believe me, check out Tiger Direct and New Egg and see
the comments.. Some don't even work out of the box.... There are dozens of experiences explaining how they had to RMA the card after
just a few months or even weeks.. The links I provided to you are the fastest AGP cards available today.... If you truly want to go with
an Nvidia card, I would suggest a 7800GT/GS if you can find one.. But understand, most likely it will be at a premium(expensive)..
The 6800 series is a decent substitute.. While there is a bit of a drop in performance, it is likely you'll be able to find one for much less than a 7800 series card..
In the AGP arena, ATI has definitely taken the lead(and will probably remain as there probably won't be anymore AGP card advancements)..
The 3850 has even beaten out the 8800GT is some aspects.... I just noticed that pasted I 4650 twice.. I meant to post the 3850 also...
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161226You need to understand that the 3850 is the very best you're going to get when it comes to AGP and it beats out ANY of the competition by a large margin regardless what Count Krustula says...
The numbers speak for themselves.. There are rumors that better cards have been made(by ATI), but I can find nothing as far as where to buy them or any real info on them besides a few reviews.. It is likely these cards never made it past prototype stage.. The 3850 will literally crush the 7950GT(which I think is the fastest AGP card Nvida produced).. The 3850 is basically a down-clocked 3870.. So, the overclocking potential is excellent! Check this review and comparison out...
http://www.anandtech.com/video/showdoc.aspx?i=3151&p=9If you have any other questions, feel free to skip this thread and PM me as I'm sure Count Krustula will have more bad information to spew after reading this....