ReactOS is a free, open source operating system for natively running Windows applications. Here I install alpha build v.0.4.7 in a virtual machine and test it out, including running a version of PhotoShop.
You can learn more about setting up VirtualBox virtual machines in my video here: http://www.youtube.com/watch?v=jyi-N...
RUNNING REACTOS FULL SCREEN IN VIRTUALBOX: To get ReactOS running full-screen in VirtualBox, once you have installed the OS you need to adjust video memory and install Guest Additions. To do this, with ReactOS not running, in VirtualBox select the ReactOS virtual machine, and then click on “Settings” and “Display” and drag the video memory slider across to 128MB (you may get away with less, but for me 128MB worked).
Then launch ReactOS, and in the VirtualBox “Devices” menu, select “Insert Guest Additions CD Image”. Next, in ReactOS, open MyComputer and then the “VBOXADDITIONS” virtual CD drive (probably d:), and double-click the file “VBoxWindowsAdditons.exe”. Follow through with this process, including the involved reboot of ReactOS, and you should find that you can enter full screen (using Right-Ctrl and “F”, unless you have remapped the host key).
You will need to cross your fingers and maybe start again and repeat the process to get things working. ReactOS is in alpha, and it took me some time to get this working OK – which is why in the video I referred you to instructions here! Or you can simply test ReactOS in 800x600. :)