In the device manager > under "Universal Serial Bus Controllers"
If it has an entry for "USB 2.0 Enhanced Host Controller" then you do indeed have USB 2.0 on your system. What motherboard is it you have? Does it say it has USB 2.0 on board? Or is it that you have wired up front USB ports and are not sure whether they are running at 1.1 or 2.0 kind of speeds.
Corm