Reddit mentions of Denon DHT-1312BA A/V Home Theater Receiver with Boston Acoustics MCS 160 5.1 Surround Speaker System (Discontinued by Manufacturer)

Lots of 1-star reviews from this year, old model that's probably not going to get warranty support, I dunno. You could try it and see, and if the receiver dies (all the bad reviews claim the receiver dies but say nothing about the speakers) you can still use the speakers with a new receiver.

Here's the newegg listing, which has more pictures and specifically a shot of the back panel. I don't like the clip-in speaker connectors. They're too flimsy. I'd rather have posts for banana plugs, but the speakers don't have non-removable wires so you could always get higher-gauge wire and crimp on banana plugs if you ever replaced the receiver. But you're not going to be able to entirely avoid clip-in speakers in this price range (looks like most of the others have banana plug posts for the Front L/R mains, clip-ins for the rest).

Something worth noting with the Onkyo is that it doesn't convert analog video to digital, so if for example you have a Wii or other pre-HDMI console or VCR or whatever, you'll have to have analog outputs from the receiver to the TV and will have to change inputs on the TV when you change inputs on the receiver. Others like the Denon linked above will convert analog to digital, but they lack other things like component video input (there are other solutions for that if necessary).

I know this is a lot more than you probably want to spend, and I'm totally not saying, "Buy this and only this!", but this or this (same receiver, different speakers) is what I would consider a good "Home Theater in a Box". It's the same Denon receiver mentioned previously, with much better speakers than the Onkyo box set. Regardless, with the Onkyo or the Denon or something else, by buying separate components you'll be able to upgrade things in the future without having to throw out everything and start over fresh each time.

Depends on how picky you are and how much control your receiver/amp gives over sound distribution. It's a good set for a first Home Theater to decide if you're really into that sort of thing...but the center speaker (most important speaker in a SS) is essentially the same as the fronts/rears.

My guess is that you'll lose a lot of detail from the center due to the sub...biggest mistake I've seen most people make when initially buying a HT system is craving too much bass...you really lose a LOT of whatever you're watching if your sub overpowers everything else.

And for receivers...look at Denon. Actually, if it's your first HT system, there's an all-on-one with a Denon receiver and Boston Acoustics speakers that's pretty good. $100 out of your range, but you may be able to catch it on sale.

I bought this unit http://www.amazon.com/Denon-DHT-1312BA-Acoustics-Discontinued-Manufacturer/dp/B004U40598 years ago for under $400 and it still works great. I would look for an all in one package that doesn't have speakers with special proprietary plugs (so you could use the speakers with a different receiver if needed). If you aren't an audiophile these systems are a good choice. Also the receivers handle all of the video switching (4 or 5 HDMI in, one out to the TV) and pairs well with a logitech harmony universal remote. Just get an extended warranty through best buy or something for reassurance. Good luck!