Get rid of the soundcard unless you really need it for some reason, onboard is good enough now

Get more RAM, no point running Vista64 is you aren't taking advantage of it...though as pointed out in my hardware thread, WoW is only a 32-bit app so will still be limited to a 4Gb max address space. Having 8Gb RAM though will allow you to run vista without a swapfile which helps eliminate drive thrashing, and other apps and OS portions can be allocated to the 4+Gb address space so you will see more available RAM for WoW then if you were only running 4Gb