This one works in batch to calculate the PUID of all selected tracks, the tagger script uses the PUID to get metadata for the track. The tagger script also performs the GUID generation if it needs to, but this script can do that first, which will speed up the tagging. You can also use the PUID for duplicate checking, etc.
Download my scripts at trixmoto.net. If you're interested, check out my Uniface blog. All the code for my website and scripts is safely backed up immediately and for free using Dropbox.