If you can install VMware server on Windows 2003 then you’ll be able to create a VMware virtual image. After the image is created, load the image with VMware player which works on Win2k, WinXP, and Vista. When the VMware image boots you can install any OS. Lastly, load the image on the VMware server to install the VMware client tools after the OS is running. Here’s an example of WinXP Pro running on Vista in a window.
