i have not heard much on cambridge speakers
you could also look at $329 refurbished w/ shipping - onkyo HT-S650 http://www.shoponkyo.com/catalog.cfm?id=3
click club onkyo price, click register, click join now then you will see the special club price or the $449 HT-S760 6.1 system with free dvd player (club onkyo)
i have listened to these systems and they sound surprisingly good, in fact they ranked them really high over at CNET equipment reviews, the best part is they are complete with a 150w powered sub, so you got a nice platform to grow from...
you could just hook up the sub and fronts and save the rears for later...i personally would get a small integrated amplifier and a pair of good ~ $300 speakers like B&W DM-303. That is similar to what I am running now at home, very space effective and sounds far better than my H/K receiver, even without the rear and center speakers, the sound is so clear and real that they are not missed. For a small amp you could go with a new Cambridge for $199, they also have a A500 Integrated Amp with remote, a demo unit, for $225 at http://www.audioadvisor.com/store/clearance.asp you could also look at used NAD, Creek or Rotel gear at ebay or audiogon..... this will give you the best possible music sound for the dollar