FOK,
Sorry to hear of your woes. Sounds like you might have had a "Friday afternoon" machine the first time around.
With regard to your exploding battery, you might have some comeback if it was one of the units covered by the following programme:
MacBook Pro Battery Update
The MacBook Air is "kewl", but lacks the punch (by a long shot) of your 17" MacBook Pro. There is supposed to be an event in the middle of October, possibly releasing new MacBooks. Remember, if you buy from an AppleStore, you have two weeks to take the machine back and get a refund –*handy if the line is updated "just after" you invested in a new machine.
AppleMacster