I'm trying to load my copy of CS5, which is an upgrade disk from CS2. I have all the original disks, serial and activation numbers for CS2. But I find that the activation numbers are no longer valid. CS5 disk will not even start up on my WIN 8 machine
Nothing earlier than CS6 is supported under Windows 8.
That said you can try downloading the installers for CS5 here: http://helpx.adobe.com/creative-suite/kb/cs5-product-downloads.html