Are you fully backing up your account and planning to restore it (via migration assistant) to the fresh install? If so, all your iTunes data should be fine.
If you weren't planning on doing that, you probably should be, but even so, if you back up your full iTunes folder I believe the metadata, including play counts, is stored in there. If not, it would be in your user's Library folder, along with all your other prefs, which I assume you want and therefore are backing up anyway.