Or at least, cards that fit into a pci-express x 16 slot. Here's a filter search on NewEgg: http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010380048%201069609641&name=PCI%20Express%20x16
Let us know when you've made a choice!
You filtered out all the PCIE 2.0 cards, which are backward compatible with PCIE 1.0 slots.
The amount of RAM installed in your system (1Gb) will be a limiting factor if you plan to get a mid-high end video card. I suggest you upgrade to atleast 2Gb when installing the card.
Also, what will be the main purpose of this system?