Unlike AS or VB, JS has no move command -- you have to copy the file first and then remove the original. But this results in loosing creation, modification date, lables, etc of original files. I wrote a function to solve the problem. See move files function here.
Bridge's thumbnail objects have a copyTo() and a moveTo() that could be another option for you if you have this app to communicate with…? You need 2 thumbnail objects one the file/folder object to copy/move the second a folder object for the location…
I took the basic element of your script and it worked, thank you very much, but not before I had an interesting issue that some may have hit before. I am using CS5 on Windows 7 and my VBS scripting didn't work until I opened Indesign using Run as Administrator. This seemed to set a bunch of elements around the Type Library. Once I then quit out again the script ran fine. Before that I was getting 'unable to open Adobe Indesign CS5 type library' errors.