http://www.oldversion.com/program.php?n=coolpro
not sure if its works but they have all the versions of cool edit.
Not exactly all versions, and not freeware either, but shareware.
Though, Cool Edit 2000 is quite usable, even unregistered. The limitation is that you can not use all the effects in one session. You have to restart and select a different set of effects in order to use them. However, later versions disable saving to disk after several days (I didn't check if that's the case with the version from that link above).
Cool Edit Pro Demos on the other hand, aren't really usable, as they quit themselves after several minutes, can not save to disk at all, and have even the clipboard encrypted, so you get crippled noise when you try cut and paste into another software.
The really old versions (those with EGA graphics) don't have any limits, iIrc, though as they don't have anything better than 16 bit support, they are only suitable for very basic editing. Even simple fades naturally will degrade sound quality.