Suggestions for POST Diagnostic Cards?

antis0c asks: "I have a number of PC's of mine, and family that have stopped working, or caused other odd unknown failures such as 4 different harddrives, different brands, all becoming physically damaged in the same computer. General fixing is as easy as removing some hardware until the problem goes away, then putting it back until it comes back, thus narrowing down to the single problem hardware. However more tricky problems require a POST Card. I've never purchased one before and I think I could get more use out of older hardware if I did, and I was wondering if the Slashdot community had any suggestions and comments on the various brands out there such as POSTmortem, MSD PostCodeMaster, and PC Engines. Thanks."