I’ve found what might be a good tool for checking your Western Digital SATA drives.
It’s called “Data Lifeguard Diagnostic”
You can download it from here http://support.wdc.com/product/download.asp?groupid=606&sid=3&lang=en
But you might want to check this page, http://support.wdc.com/product/download.asp?level1=6&lang=en first to find your model of disk and make sure it is compatible with the tool