newegg makes errors every so often, meaning if it's the manufacturer's word vs. newegg's word, go with the manfacturer (they are about 20 times less likely to be wrong)
as to graphics cards
the 9550 and 5500 are rarely run in bencmarking, as 64-bit and 128-bit versions of both are avliable
both cards cost in the range of $100
the 9550 is an underclocked 9600np
If I were you, I would purchase the Radeon 9600XT for $100-$105 on newegg, as it's one of the best values for $100
if you'd like nVidia I would suggest the GeForce 6200 AGP, which iirc is $109 from newegg, the 6200 is roughly the same performance of the X600Pro 128 and X600Pro 256, BUT I don't know how the X600Pro or the 6200 stack up to the 9600XT (i'm guessing their near each other, as all are 4 pipe cards with 128-bit memory interfaces, so I wouldn't guess that the 6200, 9600XT and X600Pro would be amazingly far apart in performance)
I would also look at the GeForce 6600nU (don't be tricked into Chaintech's Value series 64-bit version, it'd be horribly slow) as it's in the range of $145, and is easily faster than anything else suggested thus far (6600nU = X600XT, 6600nU is one step under the 6600GT, which is roughly as fast as a GeForce FX 5950 Ultra...so the 6600nU is probably simmilar to the GeForce FX 5900 or 5900XT/SE)
as to the top end of my suggestions the GeForce 6800 takes it, the 6600GT is around $190-$210
the 6800 is $239-$275 (Depending on which OEM you choose, and what they are including, but XFX's card keeps it cheap, and XFX is a GOOD brand)
the 6600GT isn't cost effective when the 6800 can be had for $40 more (if you can't get $40, then by all means get the 6600GT, but i'd say get the $40 and get the 6800, as it'll provide faster gaming and be generally more powerful)
since your looking at a relativly low end card in the $100-$125 segment, I would suggest going with the 9600XT or the 6600nU
the Radeon X600 and X700 series are (sadly) not avliable for AGP, nor do I believe they will ever be (sadly, as the X600 offers good performance at a nice price)