Da5id-
You're a prince of a guy for wanting to "beef up" your sister's AV situation, but the Bose system doesn't lend itself to easy tweeking. I see two options: one, she likes what she has now and is humouring you; or two, she wants better (probably because she's seen your AV setup). For case one, take back the Panasonic stuff and help her pick out a better TV (or washer/dryer, or microwave, or coffemaker, etc.). In case two, move the WHOLE Bose system out (speakers and all), and start shopping for better speakers to go with the electronics you bought her. The painful truth about the Bose acoustimass systems is that the speakers may well be the weakest link in the stereo chain.
Bryan...sorry 'bout that...