You'll also need a spacer for a 7 speed cassette on a 8/9 speed freehub, so while you're over at Sheldon's page peruse this one http://www.sheldonbrown.com/speeds.html.

The rest of the bike is okay but both wheels got trashed? Is there a good story? Hopefully with a happy ending...

A hint for posting, providing as much information as possible is a good thing (like what kind of bike, names/models of components, that sort of thing). Mindreading is hard.