I have installed Sun Virtual Box in My Windows Vista Box(Core 2 Duo 2.6GHz and 2GB).That is not bad at all. I have VMWave Workstation before. At the hosted OS, VMWave Workstation seem to be used less resouces. If I opened a vm, my hosted OS are running smoothly. But if I run a vm in Virtual Box, my Host OS is very very slow. But Virtual Box is free and VMWare Workstation is a commerical application.