The desktop is just a folder, default is x:\users\your_username\desktop
You should not need a VM to access it.
Some virtualization products will allow you to use a physical disk and boot from it.
You'll run into some driver issues since the VM hardware will be completely different than the original system, and likely be forced to reactivate Windows due to the hardware changes.
What you want to do is referred to as hard drive passthrough.
VirtualBox is one solution that's free and offers this functionality.
More detailed information is here: https://www.virtualbox.org/manual/ch05.html
Keep in mind, this isn't a trivial procedure and can be very complicated.