if you have a motherboard with no agp,maybe it can be a better buy to buy motherboard+agp card than only a pci card...
There are not very much pci cards,and they are pricey,for example,you have an 8400GS (new):http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4104561&CatId=319
if you don't game you can even buy and lower price/lower spec graphic card,because pci bus will hold on performance too...
With this type of graphic card you can plug 2 monitors,for more than that,you must buy a matrox one,but you will have to spend much more.
If you like used deals,you can buy a lot of things,from 3dfx voodoo cards,ati cards (there were old ones with tv tuner I guess),or even nvidia,or matrox.
But if you say that in windows98se you can get that resolution,maybe it is only a configuration problem.
Hope it helps..