Thanks for sharing this info. I've used all these tools and I also find WSUS Offline Update to be the best of the bunch, but it's install process takes much, much longer it seems. I've never benchmarked it, but I've always wanted a tool which downloads windows updates so Windows update SEES THE UPDATES DOWNLOADED.
The native Windows Update utility seems to install the updates the fastest in my opinion, and since we mention slipstreaming, is there a nice tutorial on that too with something such as nLite? I also apologize in advance for anyone who wishes to slipstream Vista.
There is another tool, actually, for XP, which will download only the cumulative updates since SP3 to it's end of life without any duplicates and every file slipstreams correctly but I don't remember it off hand. I used it to update our Dell XP Install discs when someone at work creates a really big computer problem for me.