in case you are wondering
I reinstalled after getting my quad core (needed so that wow itself finds it, but meh)
then i put up the symbolic linking of my folders
and i put the following setting in the config.wtf of each client:

Main:
SET processAffinityMask "2"

slave 1&2
SET processAffinityMask "4"

slave 3&4
SET processAffinityMask "8"

if you check your affinity in the task manager your wow clients should be running
main: cpu 1 (your second cpu since cpu0 = first cpu)
slave 1&2: cpu 2 ( your third cpu .. bla bla)
slave 3&4: cpu 3 ( your fouth cpu .. bla bla)

hope this simplifies the cpu affinity a bit

<edit> copy paste mistake