I bought a brand new WD Black 640 GB Hard Drive. I added it as a second drive (formatting it MBR) amd then dpwnloaded HD Tune Pro (trial) 4.50 and tested the drive. I am running Windows Vista Ultimate on my primary hard drive.
HD Tune gave me the following numbers:
Model: WDC WD6401AALS-00E8B0
Minimum Transfer Rate: 52.1 MB/s
Maximum Transfer Rate: 84.8 MB/s
Average Transfer Rate: 71.1 MB/s
Access Time: 12.7 ms
Burst Rate: 192.6 MB/s
My 3 year old 750 GB WD AAKS gets better benchmark scores than the 640GB Black. The Health of the 640 Black drive is fine and there are no errors on the drive when I do an error scan.
I just have a one line suggestion for you - Do not care about the synthetic scores.. Let that work be done by the website reviewers.. All you should be concerned about is the real world performance.. Load up your favourite or most used apps on the drive and check for any speed ups or slow downs.. That should give you the most accurate feedback..