sure you can try:

8600 GT 256MB PCIe
8500 GT 512MB PCIe

this is from www.pny.com the site that actually sells it. also you can try evga (which is what I use) this link has a wide range

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010380048+50001402&name=EVGA