VMWare Fusion - Running Windows Natively From A Bootcamp Partition on OS X

Solution 1:

From the Getting started manual:

To create a virtual machine from the Boot Camp partition

1. From the Virtual Machine Library window, select Boot Camp partition, which is automatically detected, and click the run arrow.
2. Enter your Mac password to access the Boot Camp partition. You must have administrator privileges to use the Boot Camp as a virtual machine. VMware Fusion creates a virtual machine from your Boot Camp partition and starts Windows.
3. After Windows boots from your Boot Camp virtual machine, VMwareFusion starts the installation of VMware Tools to enable full virtual machine functionality and optimize performance for your Boot Camp partition when used as a virtual machine. Follow the onscreen instructions and restart your virtual machine when prompted.
4. When the VMware Tools installation is complete, reboot your computer. The first time you power on your Boot Camp virtual machine after installing VMware Tools, you will need to reactivate Windows.

Works fine, though sometimes a second copy of the bootcamp item appears in the selector menu, this is harmless. Virtualised XP is great!

Note Parallels also allows integration with Bootcamp, and it may be possible though seems not well supported in Virtualbox...