BigV,
The Inspirons usually don't have the diagnostic partition, the Latitudes do.
The UBCD is updated more often and has some seriously good tools for checking RAM

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Dells are well-known in my book for changing how they work with Linux with each BIOS update. The Gateway laptop at work sitting next to me has the same issue (wouldn't boot OpenSUSE without a BIOS flash to the most recent version).
If you really want to test a laptop or desktop, attempt to load Windows NT 4.0 on it. Since the OS runs in a continual "busy loop", it stresses your hardware significantly more than Linux or later versions of Windows will. I've successfully tested servers with this issue that ran Linux fine

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