As of a few days ago, using Tom's Hardware hierarchy of video cards based on performance, the XFX 5670 is the fastest (best perfoming) card available in a single slot width package in the list - available from newegg.com.
In the list, it performs better than a GT240 by one level (not much), is DX 10 / 11 capable, and is available with 1GB DDR5.
Whereas the 9800GT and 8800GT (same level) may not be as new of technology, or available with the newest shader, or as much RAM.
My particular situation requires a PCIe single slot width card, but I want as good as I can get. I'll get the 1GB version, and I might get 2 of them, for separate computers now, but later on I could Crossfire them together in a single computer (when the situation changes).
mandarin