We have a new Architect who is using Windows 2000 w/ AutoCad 2005 on a PC (plenty of processor power, plenty of memory, etc.). ArchiCAD 10 will not run on Win 2000 - only on Windows XP Pro or it's 64 bit brother, at least as far as I can gather from "System Requirements" for AC10. Can we get an external HD, load Windows XP Pro onto it and then AC 10 and have both accessible. It's easy to do on a Mac, but I'm not sure about doing this on a Windows PC. We're getting ready to send him to "school" for AC10, but need to have both AutoCad & AC10 available during the transition. Can it be done using the PC he's currently working on?