Yes you can. Here is an article which my help.
http://support.microsoft.com/default...b;en-us;316941
If you go to the Install Windows XP to a new folder section of the article and follow the steps there.
The only difference with a new install is instead of choosing leaving current file system intact (step 6) you would choose to format in whatever file system you would prefer.
"Alan P. Biddle" wrote:
> Ron,
>
> >>If you already have XP installed then qualifying media is not needed.
>
> So since XP is installed, I could now do a clean install with my
> upgrade disk?
>
> Alan
>
>