Vista - Guest OS CPU Maxing out

Hello,

I am running a dual quad core CPU box with Hyper V. One of my guest machines
runs a pretty CPU intensive app that frequently maxes out the CPU of the
guest machine. While this CPU is maxed, the CPU of the Host is only running
at about 10% or so. I would like to make better use of the CPUs on the host.
I have tried playing around with the weight, alotting it to 1000 when all the
other servers are at their default but this doesnt seem to help. The guest
machine also has more than enough RAM alotted to it. Anyone have any ideas?

Thanks