you have disk and serial number?
if not the former you can probably download it from adobe. as for the latter you should have that, especially if you registered with adobe...
Actually, no. CS for Windows cannot be installed ever again, on any computer. However, a replacement download of CS2 is available for registered users. Error: Activation Server Unavailable | CS2, Acrobat 7, Audition 3
If you really are talking about Photoshop CS (from 2003) then forget about existing discs and existing serial numbers. They won't work.
The activation server for CS2 (and earlier versions) was decommissioned by Adobe a couple of years ago. Now you must download a new non-activation version and license the software with a new non-activation serial number.
See here for non-activation CS2 installer and new non-activation serial number.
There's no guarantee that CS2 will work on Windows 8 but there's no harm in trying.