How do i configure windows xp to output sound thru my HDMI

This is actually quite simple.

Click:

Start>Control Panel>Sounds and Audio Devices>Audio tab,

The first choice box is labeled "Default Device" and the HD video card is one of the choices. Make that choice there and click apply and then Ok.

 
You're missing some drivers. Go to the AMD site and download the latest video drivers, Link to AMD HERE

Click "Support and drivers" and then fill as appropriate for your card.

Look for problems with your system devices in Control Panel (System). You may be missing other drivers as well.