Key type will show "MSDN" instead of "Retail"
I'm sorry, but this is not true. MSDN keys show up as "Retail" in any PID Checker.
Try this MSDN Windows 7 Home Premium Key for example: HWP76-QR9QT-4F77C-T2BJQ-6JQ4R

Anyone is welcome to try that key in any PID Checker. It will show up as a retail key. I don't know why members are trying to pass MSDN keys are "Retail" keys but they are not.
If your key is really from MSDN account, then maybe I have been wrong. I just checked a MSDN Office key and it showed MSDN so I've thought all MSDN keys will show "MSDN", maybe Windows key is different.