which quad core CPU do you have?
Does it have support for hardware virtualization (E4000 does not apparently)? Intel VT works brilliantly with Parallels on my dual core T2600 (guests run at near-native speed if affinity is set correctly, with negligible overhead on the host, however Parallels virtual networking support is very limited compared to VMware).
Intel Core2 processor Q6600 (2.40Ghz 1066FSB) w/Quad Core Technology and 8MB cache
As in my post - I have no problem running guests - actually the CPU is lower running guests than when no guests are active. In this state (no guests running) is when the Host Agent service seems to run hot
Have you tried disabling debug mode Under Virtual Machine Configuration, select the Advanced tab and deselect Record runtime information.
Tried that - still running hot.
I actually notice very little difference in CPU utilization with ot without any VM's active.
CPU goes back to normal when I stop the service
I guess I will have to live with this for now - just start the service when I need to use a VM
The Host Agent service is barely ticking over on this T2600 Win2k3 box, whether or not guests are running.
Apologies for the diversion onto hardware virtualisation; I'm a bit curious about how the various versions of Windows (Vista in your case) handle multicore CPUs with IVT support and increasing cache sizes.
Have you tried setting the processsor affinity for the Host Agent process, so that it runs mostly on just one out of the 4 cores (I don't know if vista will even let you do this - you might need sysinternals' "process explorer")? There might be a problem with the way Vista is dispatching the Host Agent's threads; context switching to different cores leading to cache invalidation problems - that's just a wild guess.
I'm not so sure VMware Server beta 2 always takes advantage of IVT. It might be difficult for you to tell with a CPU like that - performance may look reasonable even if IVT is not being used. The overhead associated with running Win2K3 on Parallels with VMX enabled appears significantly lower than with VMware Server beta 2 (with peaks in CPU usage being noticeably shorter in duration). However I am not using Vista (only Win2k3 and XP), and it seems likely there could be significant differences in the way these OS' handle dispatching WRT the features on these newer CPUs.