Renaming a series of indexed files with Powershell

I love Powershell. I am only halfway through Bruce's book, but I am getting already a glimpse of its potential. I like especially the dynamic aspect of it. Creating and extending types on the fly is something that is quite exciting. Next I am looking to find a solution for my open issues with sorting hash tables. I think building a custom PSObject type with an integer NoteProperty and a NoteProperty that holds a FileInfo object might get me a few steps closer to solving the sorting challenge.