Oh, I see, uhm, ok, then I'll have to guide you.
First, click here (
http://www.ati.com).
On the top you'll find a button called Drivers and Software. Hover over it and a drop down menu should appear. Choose Window XP.
Next, Windows XP Drivers and Software, typed in red.
A new page will load listing different catagories. Choose the Radeon.
On the next page that loads, pick the top option, the Catalyst 5.9 Windows XP - Driver Download.
You'll get a list of 2 types of drivers. You'll have to find out which one you need, if you have the Catalyst software already or not.
To find out you can bring up your Monitor Properties Menu (Right click on the desktop is one way, and choosing Properties). If you see Alternatives (or something along those lines there) among the usual General, Card, Monitor, etc..., click it.
If you have the Catalyst Control Center, the word Catalyst should appear.
If you're still in doubt, choose the download that doesn't contain the Catalyst Control Center.