Performance Issues...

So, after a Vista re-installation, a quick listen to the fan showed that the CPU was working overtime. Investigation with Windows Process Explorer showed that this was down to DPCs (Deferred Procedure Calls), but didn't show what was causing them.

Then I found this blog which very quickly identified the Intel 82562V Network Adapter as the cause. All you need to do is turn off all the Power saving and Wake-on-Lan settings in the Power Management tab of the Adapter properties.

Easy as that...!