XPpro not recognising flash disk

My 2 year and three months old desktop computer system started to play up. It wouldn't recognise USB printer and other devices. I told the system was in need of a reformat.
I formatted the hard drive and Reinstalled xp pro,it went without a hitch.
I installed a new pci card with 5 USB 2.0 ports, as i only had usb 1.0 ports previously.
Now the system will not recognise my thumb drive (flash disk). It installs it as a unknown device. Everything else works perfectly. Including usb printer. Usb adsl modem > usb digital camera.
I have tried all i could think of to make this thumb drive work but it will not.
Previously the thumb drive worked 100% on this system, and currently works 100% on any other computer running xp.
I cannot run any drivers for the thumb drive as the only ones supplied are for win 98 and xp will not read them. I updated the driver for the pci card and it made no difference.

Additional information:

Thumb drive > ASTONE 256Mb
Leadtec mother board
AMD Athlon 2000XP processor
512 RAM

Diagnose/troubleshooting:

=Updated driver for pci card
=Attempted to find a driver for ASTONE thumb drive
=Uninstalled and reinstalled all of the usb host controllers and root hubs
- tried the thumb drive in all 4 new 2.0 ports and the old 1.0 ports
-followed all WINDOWS trouble shooting advice
-

did you try add new hardware.......??more info on system......make model used......

Yes i tried to install new hardware but it says it cannot locate a
better driver match then the one currently available.
My computer was built by a local IT shop ad i brought it brand new a
bit over 2 years ago.
it has a Leadtek (winfast K7n415DA) motherboard, AMD Athlon 2000XP
processor, 512 RAM, 40 gig Western digital IDE hard drive, Win XP pro.
I have 2 x USB 1.0 ports from the mother board and 5 x USB 2.0 using
PCI card.
What other information should i supply?
Thanks