Quote from ArchAngel:
1. If the USB version isn't noted on the PC near the USB slots and it's not specified when you look at the USB controller in the Windows Device Manager, then you'd have to check your PC's user guide or product specs.
2. Devices are usually backward compatible, but unlike to be forward compatible - i.e., you could usually run a 1.1 compatible device plugged into a 2.0 compatible slot, but you would not be able to run a 2.0 device in a 1.1 slot.