Some have gotten the 9250 to work on Windows 7 using XP drivers. The 6.14.10.6606 version has been recommended, but you may have to go to the torrents to find it.
Otherwise, at
www.newegg.com, the cheapest DX9 card uses an nVidia 5200 chipset. The 8400GS is a bit more ($40), but it's DX10 and perhaps with better performance.
Maybe staying with XP would be your best choice, though.