The other day I did a P2V migration on a server 2000 machine that had 2 CPU's and 256MB of RAM. After the migration I changed the specs to 1vCPU and 512MB of ram, the box runs fine and CPU usage reported by server 2000 is around 5% or lower but VMware is using 2Ghz or more for the box (I also have another server 2000 box that is running with no problems). Any ideas as to why vmware would be doing this? fyi I am running on ESX 3.5.0 build 82663.
If you have any other questions about config I will be happy to answer them.
I ran into this exact same problem about a week or two ago. Search for posts by me from that period and you'll see my thread. I ended up just changing the HAL on the 2000 VM to a single processor hal and assigning a single processor to the VM. Problem went away.