In repeated tests, VirtualBox on my otherwise smoking-fast Macbook Pro is a total bust. It is so painfully slow that I can't even get one of the started desktops to shut-down. I was able to use VirtualBox on the Mac to convert the disk image to the format for VMWare Fusion to open and use. With only that change, and whatever post-start-up stuff Windows did inside the VM, the machine started quickly, is responsive, and blends (possibly too much) with the Mac UI.

I've also installed a copy of the current release of Ubuntu (10.10) and the Alpha for the next release (11.04). Fusion doesn't like running more than one VM at a time (a problem I had with VirtualBox only when the total RAM of the VM came close to running my host out), but I'll deal with that as it comes up.

Sad to say, but it turns out I need Windows for some things, and I miss some of the Ubuntu tools for which I have yet to find counterparts. Also, this gives me browsers and such on three platforms on one machine.

I've dropped the coin ($80 today, $30 rebate already submitted) to purchase VMWare Fusion, and actually uninstalled VirtualBox (remount the DMG and run the uninstall script). I'll continue to use VirtualBox on the other systems I have, where it does still rock with full-speed access to the CPU, near as I can tell. Perhaps a future release wil address the performance, but for now, VirtualBox is off the Macbook Pro.

For others in the same boat, use the following one-line command to convert your VirtualBox VDI image to a Fusion VMDK image (your path an file names may vary). Copy the VMDK image to your Mac (if you didn't copy the VDI first and run the command there), then build a new VM using the VMDK as the storage.

VBoxManage clonehd VirtualBox.vdi Fusion.vmdk --format VMDK

I recommend trying to match your previous settings (like RAM and other devices) as closely as you can; Windows will complain that your copy is invalid if too many changes are noticed at once.