This answer may accomplish nothing more than showing my ignorance, but I am noticing that Office(currently) names the office folder inside C:\Program Files\Microsoft Office numerically in sequence as new versions come out. I don't know if they always did it this way(I don't have an older machine to check on), but if this is the case, one could just check the folders that exist there. If you find an "Office10" folder, Office XP is installed. I have a Beta version of Office 2003 running, and it is under "Office11". Does anyone know if they used this same format in previous versions and if this would work then?