Hello,
No, you just can install PT 2008 in the same folder as PT 2007. By this way you will keep your Settings, Snapshots, Tasks and Backups of PT 2007.
But your folder will still remain named "jv16 PowerTools 2007".
If you will uninstall PT 2007 just save first all your Settings, Snapshots, Tasks and Backups in a save place, to re-integrate them in a fresh install of PT 2008.
Regards
Jean-Paul