Which VM (Virtual Machine) is best for IM programs?

Vmware too OS XP !

Version 7 required ! And you can find some pre made OS image over the web so you don't need a DVD !

Okay, gonna give VMware a go. Since I bought Fusion (the Mac version) but don't use it, I'll see if they can change my license over to PC. I really don't want to buy it again. If they make me buy it, I'll go with VirtualBox.