Hi blackroses - hope you've got this problem fixed by now, but if you haven't there's a couple of things you could try.
1. Search your hard drive for the image. Click "Start," select "Search" and choose "For Files and Folders." In the search results box choose "Pictures, music or video" and search for All. This might be slightly different with Windows XP, but not much. You'll get hundreds of results, most of which will be icons and junk, but you might get lucky.
2. There are software programs that claim to be able to restore lost photos. I've linked to a free one below, though there are a number of alternatives which may be better. I don't know if this is any good, but I trust the website it's posted on so I'd suggest it wouldn't do any harm.
Best Photo Recovery - Free software downloads and software reviews - CNET Download.com
Fingers crossed for you.