Hi -
No, the Bose will only give 'simulated' effects, and some TVs or other audio equipment also has a 'wide' feature, but only achieves it by messing about with 'phase' effects I assume, and can sound grim and very unrealistic!
Why is your state of the art wiring obsolete? 'Wireless' isn't essential is it, and can introduce it's own problems?
What sound systems do you already have, for CD, radio, etc, as could some of that not be integrated into a surround system?
26'X15' is a good size, but ideally the TV should be roughly in the middle of the 15' side, so you can sit well back down the length of the room.
A surround amplifier has controls to balance each of the four 'corner' speakers, plus a centre channel (to avoid the 'hole in the middle' effect), and a sub-bass speaker, which can be placed almost anywhere I think.
Don't want deflate ambition, but I don't think you will get much for £200. My stereo system was around £5K, and that's only just above 'entry level'. A serious enthusiast would add another 'nought' to that.
Another factor that has a huge effect on sound quality is the size of a room, particularly the height. My system can't really 'communicate' in our low ceilinged bungalow, but twenty years ago I used my previous system in a large hall for a social club 'record recital' and it was sensational. Normally, speakers shouldn't be placed too near any walls, as reflections will cloud the spacial 'image'. But conversely, people who really know what they are doing, can use walls to their advantage.
So, weigh up what you already HAVE in the way of amps, speakers etc, then go online to specialist surround sites, and glean more information (even though you aren't considering their prices.)
I guess, if you go for the multi-channel amplifier/control unit first, then add the speakers and sub as you go along, might give better results than doing it all in one go.
Also, at 18 if DS is creative he could possibly make some of the speakers (from on-line plans) only needing to buy the 'drivers'. And creating an ultra-low 'sub' could be a real achievement!