Basically all the old files are only good for historical reasons. I was hanging onto mine but finally decided I needed the space more.
The download descriptions tell the story though. If you have *any* version of 1.03 (including the original full download which I think was manditory), then the AH103T1034.EXE file will update you to 103.4. In other words, you can trash all the other 1.03 updates and just keep this last one plus the original 1.03 full download.
Advantages to downloading a single file? If you ever need to do a complete reinstall you only need to run the one file instead of a base and then an update. Also, if you give a copy to anyone on CD-ROM, Zip, or spanned floppies, or other method, they also only need to install one program and the overall size is a meg or so less.
But that's it as far as I know. I'm pretty sure downloading and installing from the single file gives you the same footprint as the base and update method. It looks to me that the updates just replace updated files in their entirety.