Hmm... Missed that one when I was looking. To be honest I'm not sure about the x1300 series. I know that some of them use hypermemory (shares the RAM) but this one doesn't seem to.
It could be a little slower than the 9600XT. The 9600 has a 500 MHZ core and 600 MHZ RAM and 4 pipelines, and the x1300 has 450 MHZ core, 500MHZ GDDR2 RAM, and 4 pipelines.
Maybe they're similar, or the X1300 with its 256MB and GDDR2 can compensate for the slower frequencies.
Hey Wolfram! Yeah, I was kinda thinking the same thing but I wasn't sure if the x1300's had any of the issues that the x1600's have had. I guess if it were me I would go with the 9600xt just for the higher clock speeds.
You need an nVidia 6600 at the least. You could search around for one, but it'll be just above your budget. Any lower spec card and its not worth upgrading honestly.
I personally do not like Nvidia Vid Cards. They seem too overated, and are menat for games like Doom 3 and Quake 4, which I do not play. I stick to games like Oblivion (don't own it, just an example). ATI cards have been proven to work better and faster on brighter games that do not use as many shaders. I usually do not play games with these anyway. What about the 9800?