ultimate boot CD

Ryan put me onto the excellent memtest86 utility for checking the RAM integrity on your system. When I needed to test my workstation at HVS and I asked for memtest, Mark handed me the Ultimate Boot CD v3.0 (which has memtest on it).

This is entirely OS agnostic, and an excellent thing to have around not only for when you have problems, but also when you may have doubts about your setup or intermittent flakiness in your system.