I think you can still find the trial installers (which are identical to the licensed version, just add a serial number) at Download Adobe CS4 and CS3 Free Trials Here (incl. After Effects) | ProDesignTools
Be sure you read and follow the direction on the page EXACTLY or you will not be able to download.
It's nice to know that the old software is still available! My copy is part of CS4, do you think that the individual program should work with the suite serial number and activation key?
To correct my previous post, the version that crashes on my computer is 6.0.6, and 6.0.5 seems ok but sometimes won't open files with error message 14 (file not compatible with ID)
In CS4 and CS5 each individual product can be activated with a Creative Suite Serial of those suites where it belongs to.