Sound Bars - Are they useful in upgrading sound in flat screen tvs? [View all]

I see Bose sound bars (among other brands) advertised on home shopping networks for use with large flat-screen TVs.
The sound on my flat-screen TV, a hand-me-down from a family member, has never been great, and I'm wondering if a sound bar would be the answer, or at least an improvement.
I know little to nothing re technology and would need assistance with installation if a sound bar would be recommended for my situation.
They are not cheap - Bose sound system would cost about $250.00