you don't need to get that complicated just to copy a .pst file. There is a freeware program on nonags called RoboCopy. Download it and put it on the server somewhere. Have the script copy it to the c: drive of the local machine (the program is small, wont take more than a second), then have the script run it and copy the file to the home share.

script....

md h:\DOCUMENT_BACKUP
COPY \\server\robocopy.exe c:\
run "c:\robocopy.exe c:\ h:\DOCUMENT_BACKUP *.pst /s"