I have just begun experimenting with VMware and Ubuntu. Bear in mind, I am playing with VMware Workstation. I'm finding that it's not really performing well under the circumstances. The guest OS is doing brilliantly. If you sshed into it, you'd never know it was running under Windows XP in a virtual machine.
The problem isn't with the guest OS. The problem is on the host OS side. This particular system is shared with others who use XP. I was hoping to run both OSes side by side and save the hydro of a second system. Unfortunately, the performance penalty to the host OS in this case seems to be too much.
It really wouldn't surprise me if, with a Linux host OS and windows guest OS, the entire system had far better performance. Less overhead on the host OS side would certainly alleviate the performance hit at least a little. When I finally find my Linux box among my things from Edmonton, I'll probably just bring it online and forget about VMware.