Well I did a lot of googling last night. Turns out the sound blaster audigy cards have massive vista driver issues that creative refuses to fix. But there may be a light at the end of the tunnel. A guy named Daniel K in brazil a long time ago re-engineered and fixed the drivers. He was sued by creative but his driver versions are still floating around the net. I installed them last night and made sure I still had sound coming from my speakers but it was too late to test WoW - will find out tonight if I can now 5 box without sound issues.

Aside from that I'm not hitting a CPU bottleneck so I have to decide if I want to upgrade my CPU/motherboard :\