I don't know that model specifically, but I doubt you can find a card, as such, for that machine. In most laptops, the video aspect of things is built into the motherboard. And even if it is not so integrated, it is not meant to be changed out or upgraded. There has been some movement in the technology lately to have the video card for a laptop be somewhat ungradeable, but I don't think it has gotten mainstream yet. It certainly is not like what you can do on a desktop machine.
Sorry about that sarcasm there. But really only about 1% of current laptops can replace the graphics card in them and this is a VERY new feature. If it is more than about 6 months old or so then your laptop definately lacks this feature. The other thing is these are not generally sold seperately so even with aremovable card, it requires dissasembling of the system and can normally be perchased and installed where you bought it.
VoodooPC was promoting a laptop line that had a removable card. They would also install an upgrade card for free, but of course you had to buy the card from them. Also you can generally only go so far up or down on a single platform. I think they had a 9600 and 9700 in various memory quantities and you could get the 9600 with say 64MB and trade up later if you wanted to the 9700 with 128MB. cost wise it was not that good of a deal. Likely it could not go into the 9800 range with the same platform. This is one of the biggest drawbacks about laptops. You can only upgrade a few things... memory, and hard drive basically, before you need to just replace it.
I doubt you could upgrade it very far as too much changes between models. Likely if the computer had 3 choises when you got it for graphics, those three choises would be it. That way if say you got a Radeon 9600 with 64MB, you might be able to change it to a Radeon 9700 with 256MB later, but not the 9800 or x800 later.