New Computer for 5 Boxing

[Memn]

if yeh gonna go with a 64bit operating system get like 8 gigs of memory. The only point in getting 64 bit os is so yeh can use over 4gigs of memory.

If yeh stick with 4 gigs , vista will eat 2gigs and each instance of wow will take any from 256 - 500 megs depending on setting and where yeh located.
if yeh hit a city yeh will lag with 5 chars.(assuming yer playing wow and have default install of vista...).

only time raptor might make a noticeable difference is loading into an instance

Wowphreak is dead on. Skip the raptor, buy more RAM. You won't be sorry. My memory utiliization is usually around 5 GB when I'm 5 boxing using a very similar build. Resource manager puts most of my load on CPU and memory.