I'm in the process of upgrading now, but I have been "getting by" for about 2 years now with a Boston Acoustics DigitalTheater 6000 system. They no longer make this, but you could probably pick one up on e-Bay for $200-300. (I paid $600 for mine, new.)
Can't say enough about this slick little system - all amplification is in the sub. All audio inputs are on the sub as well (one coax digital, one optical digital and 2 or 3 analog inputs). Center channel speaker has IR receiver and input/volume display. Other 4 speakers are quite small & unobtrusive - they come with wall/ceiling mounts, but they also have threaded inserts in the bottoms - I used to use cheap camera tripods as speaker stands for the front channels - looked really cool. Comes with a nice (simple) uni-remote, too.
All 5 speakers are actively equalized (probably to get the best possible sound out of the cheapest possible drivers.) Unusual approach, but it works - the sound is remarkably good - my guests have often commented on how impressive the sound is from this little system. I don't think B.A. ever published a power spec on this system - only SPL specs; I'm guessing they made the 5 satellites very, very efficient, then used little (15W? 20W?) IC amps. From a technical/construction/circuitry/specification standpoint, they're fairly unimpressive, but the sound... again, WOW!
Highly recommended. I'd put this up against any receiver/sub/5 cheap-ass speaker combo any day of the week. (I did just that, in fact, before I bought it - it sounded far better than the 2 best combo-kits from Sony & Yamaha. I had concerns about its "window-shaking capabilities", so I cranked it up in the middle of a Good Guys store... an entire store full of people stopped what they were doing to give me a dirty look - SOLD! *LOL*)
FWIW - B.A. also made a DT7000. It had a little more power/bigger sub, etc., but the chief difference bewteen the two was DTS - 7000 has it, 6000 does not.