I'm a silver-surfer with no letters after my name, just a little native
intelligence and innate curiosity. I too installed a USB2 card on XP/SP2
machine recently - cheap 2-port card.
Originally had problems, but these were overcome by deleting EVERY instance
of USB in Device Manager, rebooting, and letting XP sort itself out, after
which, all 6 original USB and the 2 new USB2 ports work just fine, as does
the new USB2 4 port hub..
My theory, based on sequence of events and initial problems seen, is that XP
needs to allocate USB resources in a specific way/sequence. And, as XP/SP2
already supports USB2, could be that the "native" drivers are all you need.
Try just installing the card, rebooting without drivers. THEN - leaving the
card in place, delete(uninstall) EVERY USB entry from Device Manager (make
sure you have a cabled mouse/keyboard in place first) then re-boot.
If that doesn't work, have a look at the entire content of the driver disk.
There may be a "readme" which gives detailed instructions. Such files always
worth looking at first, as the procedure is frequently not as
straightforward as just fitting the card, loading the drivers. (The number
of people who DIDN'T read the XP2 install "readme" resulted in HUNDREDS of
unnecessary posts!)
Do post back your results ...
Sincerely, Len.