Would a Dell Inspiron 15 with these properties be able to run Pro-Tools 8 LE? My G4 Powerbook died....?

OK, it sounds like you know what you're talking about, so I'll level with you about Pro Tools. Get a mac. Period. You've been using one for a while (clearly) and it is by far the best choice for Pro Tools. Plus, if you some day work with someone using final cut studio, it will still work.