|kuwese and anataf|
The USB 2.0 support is already there in the contents of Windows 7, but you must install the main chipset drivers for your mboard model in order for the USB 2.0 support to be installed in Windows.
Once the main chipset drivers have been installed, the USB 2.0 support shows up in Device Manager - USB Controllers , usually as an Enhanced USB controller - there may be no 2 or 2.0 in the line.
(Double click on Computer - in the top bar select System properties - the link to Device Manager is on the left side.)
Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, USB 2.0 if it has it, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.
If you don't have the CD that came with the mboard, go to the Asus web site and find the Downloads for your model.