My advice, forget 7.1 or 7.2 for now (relative to speakers), you just don't have the budget for it.
While I'm sure people are tired of hearing it now, I don't think you can beat these three deals at the moment -
From SuperFi.co.uk -
The Wharfedale Daimond 9.0 5.1 home theaters system @ £349
From HiFix.co.uk -
These Daimond 5.1 system with BK Subs -
Option A -
£97 = Diamond 9.1/
pr
£112 = Diamond 9.cs/ea
£64 = Diamond 9.0/
pr
£199 = BK Genini Sub 8"
-------
£472
Option B for BIG -
£179 = Diamond 9.4/
pr
£112 = Diamond 9.cs
£64 = Diamond 9.0
£295 = BK XLS200 sub 10"
-------
£650
These are not package deals, you have to buy the speakers individually, and the separate BK Sub directly from BKelec.com .
The Diamond 9 series have a long history of critical acclaim.
If you insist on tiny lifestyle speakers, then the recommend Kef system are as good and as popular as any. Perhaps something from Mordaunt Short or Tannoy, or a few others.
A suggestion, if you get tower fronts, get better tower fronts and forgo the Sub for now.
Alternately, you can save a little by foregoing the Center for now, and getting the sub.
Still, there are complete packages in your price range, as the above examples, and other suggestions show. I think the Diamonds represent good value right now, while supplies last.
Just a suggestion.
Steve/bluewizard