Larry, just out of interest, do you have any mapped network drives on your laptop? Only wondering because Windows always tries to enumerate the amount of space on all drives when the "save as" window opens.
If you've got mapped drives that XP can't access, it may be hanging whilst waiting for a response from the inaccessible drives. Try switching off the option "Automatically search for network folders and printers" option in the Folder Options dialogue box.

