If you want a system that is very unlikely to have known vulnerabilities, you could always try the Windows 7 public beta. The OS may not be perfectly stable, and even with Vista compatibility mode you may run into troubles installing software, but you are not alone. Drop by the Windows forum to see what others have discovered and add your own experiences.
If software really isn’t your thing right now, maybe the Trading Post will liven up your afternoon. You missed the Core i7 that was for sale, but there are a few clearances going on right now that you really should check out.