I finally found an installer on the net. Try searching with yahoo: http://search.yahoo.com/search?p=orbiterinstaller.msi&ei=UTF-8&fr=moz2
It sems to be working.

I also have the same problem. I have downloaded from two sources, and still have the same problem with both. The checksums are correct. I've noticed that the "pluto-orbiterinstaller_1.0_i386.deb" on both the CDs, I presume this is the installers, is only 2288 Bytes (2.2KB) Mabye there is a problem with this file? I've also tried to manually extract the files from it, but all I get is 0-bytes files.