Version 2.1.3 would not work for me in OS X 10.8.3
It started to download 180 files. After each file, it reported a failure, and offered to retry. Pressing the retry button caused it to continue (and fail) on the next file. The problem may be that it simply wont run from a restricted (not administrative) user account.
There is already a good review on this app, and iit will cost you nothing to try it out.
gogogorman about Garmin WebUpdater, v2.1.3