Hard drive space is very cheap.. you can buy an external 1 tb hd for $89 shipped, and a 2 tb external for $150 shipped!

That said, there are many duplicate file finder programs available for free.. but the problem you'll run into, is poser is looking for things to be in specific folders, and if you yank them, you'll start getting errors on your content.

You could merge just the content folders from the p4 runtime into the P7 one, and then delete the P4 one, unless you've customized some of the content yourself.

But if you are that tight on hd space, odds are your system cache is also going to be hurting as well.

Way too many people take way too many things way too seriously.