Probably inside their commercial strategy, Adobe has released their CS2 suite for free access. No support is provided, and the software is already a few years old. But for basic edition, this should be enough for most of us...
You may find the downloadable files under the link http://www.adobe.com/downloads/cs2_downloads/index.html ...
Still I like to stick to newer free versions (in my case, of GIMP), but it does not hurt to have this suite available for playing a bit, does it?