Well, I took a look at the download today. I got the Outpost1.rar file, and I extracted the Outpost1.iso file in it. I tried burning the ISO to a CD and it didn't work right. The CD appeared to be empty. I tried opening the ISO file with WinRAR, and it said the iso file was not recognizable.
Anyways, I created an iso file of some misc files on my harddrive for comparison. WinRAR had no trouble opening the file I created. I also took a look at the inside with a hex editor to compare. It was not quite the same format (although the data seemed to be there). I found what appeared to be the beginning of the TOC, which was nicely aligned on a 2048 byte boundary in the file I created, and compared it to the other file. It wasn't 2048 byte aligned in the Outpost1.iso file, nor was it 2352 byte aligned or 2336 byte aligned, as I've read can happen in other modes. Oddly enough the address was a multiple of 2353, which I do find a bit odd. Granted, I don't really know anything about the format of iso files or the structure of the file system on CD-ROMs, although what I have read suggests that iso files are just a direct copy of exactly what's on the CD, nothing more and nothing less.
But, case in point is: CD burning software, and WinRar are both unable to do anything useful with the ISO file in the download. Lots of people have had problem with this file in the past. Maybe it's the ISO file up for download?
There is definately valid data in the file, but it seems to be in a slightly different format. Maybe if the CD was ripped with different software, people might have less trouble with the download. Or why not just pack up the files and folders that were on the CD into a regular zip or rar file? (I'm assuming there's no invalid files/copyright protection that stops this?) Besides, an ISO file is mostly just empty space. I don't see the reason for using an ISO instead of just a straight archive of the contents.