Get and old full tower case paint it black, cut out a lexan window, add some neon to Xeon. You should be set. Just make sure you use XP Pro otherwise the secondary CPU won't be used. It's also a good idea to get the same SL spec Xeon. Look on Pricewatch, compgeeks, ebay, etc.
Congrats on the new PC. They may be old but they are still very usable.
