Lost USB 2 in XP SP2

Hi,
I have just done a clean install of XP Pro SP2, with all upgrades from M$.
Prior to this I ran W2K, in separate partion, formated this partion and installed XP.
Prior to XP worked fine (after installing W2K USB2 upgrade.)
Now my USB 2 ports are only seen as USB 1.1. When plugging in a USB 2 device I get a message along the lines that the USB 2 device would perform faster if plugged into a USB 2 port.(which it is).
Have searched M$ support , upgrades, web for drivers. The only ones I could find are for W2K and XP SP1. Neither worked. Lots of articles but nothing to solve the problem.

Everthing else seems to work OK.

System Spec MSI KT4V mobo, with Via 8235 chipset, 1 GB RAM, 2 x 40 GB HDD, DVD RW.

Any ideas?