I tried VirtualBox and ran into format issues when trying to utilize a VMWare virtual machine from VirtualBox. IOW, something needed to be changed in the VMWare virtual machine in order for it to be read with VirtualBox (actually, I think it just needed a configuration change, but I decided not to mess it with further at that point).

So, then I tried Virtual PC because I had problems with VMWare running VS2010 on a Windows7 vm (it was a vm that Gary had created and given to me). I had no problems with the VPC that I created running Windows 7 (my host machine is XP Pro) and it works just fine with VS2010 too. But, you're probably talking about Windows 7 as the host? What limitations are you running into?

BTW, I am basically a noob when it comes to virtualization, so take my responses with a huge grain of salt. I should probably try VirtualBox again though ... I did not give it a very thorough road test.

It doesn't shock me that you ran into issues using a VMWare VM from Virtual Box. I've always just re-created a VM, though I realize that's time-consuming and a headache.

The biggest issue for me is that even on a 64-bit machine, you can't use Win 7 Virtual PC to create a 64-bit VM. I needed that for a SharePoint 2010 VM - SharePoint 2010 only runs in 64 bit.