Starting an HT System for Cable TV viewing

Your room is about like mine. I'm a tad taller.

Find out the eff and impedances of your speakers.... or at least what were you using to drive them with before thinking about going 5.1.

Any recent receiver with HDMI will also have other video outputs your current TV can use. If 4:3 your cable box will likely be able to give you 1080I.... maybe 720p but the picture size will shrink.

Look at the Receivers listed above and shoot for at least the 120wpc @ 8 ohm, more will be best. 140wpc is what my onkyo says it outputs into 2ch. But it did drive my speakers without issues yet I found it lacking in control & definition, even rated at 140. As was said, many recievers rate their power unlike the common amplifier only types do.

Perhaps finding a rec that will give you a gohst center ch or virtual center ch will help out immediately and a center ch can be added later. Onkyo won't do that for you. sony does. I'm sure other's do as well.

I'd say do a 15 inch sub in that room... I've tried to use lesser ones to no good end. My DD15 does pretty good but another one would be better.

For big bang movies only, Definitive Tech makes some super cubes and a reference that are pretty good choices.

For under $1500 you should do fine with speaker cable, ICs, receiver, and sub. Maybe less.

Forget about HDMI until you get a serious TV.
There is no need to find some virtual center setting. Any pre/pro or AVR has the ability to turn on the center. This will route the material through the front speakers.

If you're goal is sound quality, then get separates. That way you can get a real amp for your real speakers. Don't get hung up on watts per channel. Just look for a name brand amp. Krell, Lexicon, Bryston, Proceed, ADA, B&K, Anthem, even Rotel, or Adcom all of these will have balls, some more than others. This list of amps will all have better control of a driver than any receiver rated at 140wpc, even if they're only rated to 80wpc.

To answer what speaker to get as a center: Anything Kef Reference that will match your fronts. Don't look anywhere else. The current model is a 204/2c or 202/2c. Find the previous year's model used for a deal.

A sub's ability to fill a room cannot be rated in inches. 90% of the time you get what you pay for. If you want a scale to rate subs on do it on price. The DD15 is a great! subwoofer. It's probably a bit on the pricey side for your needs. I'd focus more on a HT type of sub and not Audiophile type like a DD-15. Look for something in your price range from Paradigm, Klipsch, Snell, Velodyne even Earthquake if you can demo it in your room and make sure it will work with your speakers.

Eclipse911t

You can't be serious. Can you?

Don't worry about watts?

Subs are rated on price?

All recievers give a center ch?

don't worry about HDMI now?

There is a diff between rerouting center ch info into the front speakers and having a virtual or gohst center ch. Definitely. Not all do that. My onkyo does not. My sony does. you can hear the diff, trust me.

it is a prefference to be sure and not necessarily a deal breaker, just more advantageous.

such as are acquiring a receiver which has benn outfitted with HDMI 1.3a even though for now it may be unuseable, it serves one better to get it now than to wind up buyhing two or more devices later on as that approach is more cost effective. they will also have other video & audio interfaces too which will serve immediate needs.

Good bass costs more than good sound, oddly enough. Period.

Separates are the more expensive route. A receiver is the cheaper route, one box solution. Either approach will work, though the OP seemed to ask for a reasonable cost effective solution. IMO.

Don't worry about power if you don't worry about servicing your speakers occassionally or sound is not important to you, as underpowering your speakers will do mor bad than good.