I was running Windows XP Pro x64 till it expired on me. When it did, I was locked out of my comp and had to reinstall it. When I did this I was able to keep my old files but need to reinstall everything. I was hoping when I reinstall Outlook, would there be a way to retrieave the old mail that I had? It is still located somewhere on my comp I am sure. but dont know where. Any ideas?

Activate Windows instead of reinstalling!  Alternately, you could go scouring the drive by mounting it under a more compliant operating system.

It's in \documents and Settings\Robert A. Paveza\Local Settings\Application Data\Microsoft\Outlook, in the files archive.pst and Outlook.pst.