Do you have the installation cd-rom ? If you do, then run the setup.exe program from that disk and follow the instruction. OR
Go to control panel->system->device manager-> and find your sound card under sound controller, click left mouse to select and then click properties on that form. Then click driver and click update driver. That should give you option to search for a driver automatically OR from a CD-ROM drive. Select cd-rom drive if you have the cd and windows will find the driver from the cd.
You can also go to AOPEN website http://www.aopen.com.tw/tech/download/sound/aw200.htm and download drivers.
Hope this helps