Looking at the \Windows directory on the ASUS, there are several USB drivers already included:
USBMSC.dll = USB mass storage
USBPRN.dll = USB printers
USBHID.dll
USBD.dll
ISBDISK6.dll
and if you take a look at the registry, there are entries for keyboard and mouse:
[HKEY_LOCAL_MACHINE\Drivers\HID\LoadClients\Default\Default
So do you still have to search for drivers to download? I don't have my usb host cable with me, so can't look around the office for things to try yet.