ATI has a big problem with Xpress 200
 

ATI HAS A PROBLEM WITH USB on the newest Radeon Xpress 200 chipsets. If you look at the Tech Report report on the new chipset, specifically page 17 here, you will see that the USB performance isn't exactly stunning.
What we were hearing is that chipset has USB issues, but technically meets the spec. There is a re-spin coming in Q1, but ATI declined to be more specific than that. While they would not say what is being reworked, the south bridge is the obvious target for their affections.

http://www.theinquirer.net/?article=20039