Hi there MeepsterNotchy,
Sorry you are facing some issues with your WD drive.
🙁
I would agree with techgeek's point on OS drives benchmarking.
Apart from that, as you think that there may be something wrong with the drive, it may be a good idea to back up the most important data stored on the drive. You should keep your crucial data stored on several places anyway.
After that, you can test the drive with a tool that can provide a SMART report. You can run both short and extended DLG tests on it:
http://products.wdc.com/support/kb.ashx?id=CljApM
I believe it will not hurt to attach the drive to a different port(try port 0 in case the drive is not attached to it) different cables.
Cheers,
D_Know_WD