Photoshop CS2 is the most expensive piece of software I own. I wanted to migrate my license to Vista and it wasn’t as simple as I’d like. The main challenge is CS2 is an old version and Adobe claims it does not work on Vista. Here’s how to make it work anyway. I’m assuming you have a legal copy: do not steal software.

1. Get install media. If you have CDs you’re in business. Otherwise write to Adobe support and tell them you need to download a CS2 installer. Do not mention Vista; they’ll tell you that you have to spend $200 on an upgrade to CS3. They sent me an FTP link with a password for Photoshop_CS2_9.0_WIN_ACT.zip.
2. Unzip the install media. Don’t just double click the installer and run from the virtual folder; the Adobe installer will break with the meaningless errors .\AutoPlay\main.ini MAIN_FILE_VERSION PRODUCT_REGISTRY_PARENT PRODUCT_REGISTRY_KEY. Extract files and run from the new folder.
3. Run the installer. Grant it permissions via the usual Vista UAC popup.
4. Run Photoshop. Activate it.
5. Allow Photoshop to update itself. Grant the Updater permissions via UAC.
6. Reboot. (Screw you, Adobe).
7. On reboot, you’ll get an error that Vista blocked programs at startup because they asked for permissions. Run the Vista tool recommended in the error box and disable all of Adobe’s startup tasks (gamma control, updater). The error will go away and your computer will boot faster, too.
8. Enjoy Photoshop!

I’m sure there’s some lurking Photoshop / Vista compatibility problems. But I was able to edit a raw photo from my camera, that’s all I really care about. I didn’t test color management and printing, I could see potential problems there.