Some have gotten the 9250 to work on Windows 7 using XP drivers. The 18.104.22.16806 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.