Hi, I'm in the market for a used Mac Pro (this would be my first one since I bought a G4). Because Mac Pros are a pretty substantial investment, I'd like to be able to test the system to make sure it is in good working condition. I was thinking of using something like techtool pro to run a diagnostic to check components such as the logic board and memory. However, few sellers seem willing to entertain the idea; perhaps believing that my intent could be malicious. What is the best way to go about doing this? The last thing I want is to end up with a $2000 lemon. Thanks.