Virtualization poll

I’d like to hear your comparative opinions on virtualization software. That should include size of virtual pc, cpu use, networking settings, shared folders, ease of use + anything you care to rant about. I have in mind MS VirtualPC, VMWare, Parallels, VirtualBox + any other you may have used.
For instance, I have used VMWare 5.5, and it installed fine, created net connections and shared folders fine. But size of virt.pc large, cpu hungry, and installs 4 services starting automatically.
Can’t wait to hear your input.
Thank you all!