If you can set your system up to capture kernel dumps and get the MEMORY.DMP file posted somewhere online, some of us could probably take a quick look and verify what else might be in play there.

[edit] Also, I highly recommend you look up how to link all your data folders for wow so it only has to read one set of files instead of each, as Sychosis mentioned. It's a very cheap way to minimize the impact on your HDDs. The folders I have linked (I'm on XP, so I used NTFS junction points ; I use this software to do it painlessly) are the following:
  • wow\Data
  • wow\Addons (for easy updating of all clients )
I would NOT link the WTF folder as you run the risk of overwriting certain settings if you're not careful.