Yes, that is a very old version. The latest is version 5.0, I believe should still install on XP, although officially tested on Vista, win 7, win server 2008, and win 8 beta.
You can download the latest version by visiting
http://msdn.microsoft.com/stocktrader. You should just delete the existing install directory, and when installing 5.0, specify default install location of c:\stocktrader.