*cracks knuckles and presses hotkey*

64bit, Vista, 8gb ram and WoW: Don't bother, World of Warcraft is a 32 bit application and runs on a 32 bit emulator in Vist64 called Windows on Windows (Yes WoW-on-WoW) and is still limited to the same restrictions you are accustomed to. That said, ram is cheap, other games are 64bit compatible, hopefully Warcraft will be one day, but don't expect ANY performance increases due to using more than 4gb ram.

To test your theory about RAM utilization. Disable your pagefile.sys Since you have 8gb, and only use 5, there shouldn't be any problems... Don't worry, the bluescreen is not permanent, and re enabling paging is as easy as disabling it.