The work around I have is to open PS as an administrator, you will then get a warning dialogue from Vista saying an unrecognised program PSCS2 wants to access your system , click to allow this. In PS you can now complete the registry pop up or click do not register. Close PS and go back to the properties dialogue and uncheck the open as administrator box this will then get rid of the Vista warning about an unrecognised program. 

You only need to to do this once, afterwards PS will open without any problems. 

The issue is one of PS not be able to write to the Vista registry files unless it is opened as an administrator.

Sorry I have not come across any work around for Acrobat 7 which just seems totally incompatible.

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html