Richer Sounds are good for budget equipment, but you cant demo in their shops now (at least i think its all now, possible a couple shops still let you)
Sevenoaks sell just above budget up to fairly high end equipment, they have demo rooms, staff vary from being a bit snobbish to being very friendly and helpful.....avoid the younger members of staff is my advice, they tend to want to sell you something rather than sell you what you want.....
audio-t i've never been in, but have heard some good stuff about them.....
you say no budget limit, but what roughly are you talking about? a few hundred for the receiver amp? a thousand? a few thousand? and likewise for the speakers?
all in for a grand, then go Richer sounds for a Yamaha receiver and either Pioneer or Panasonic DVD player, then go Sevenoaks for a Monitor Audio Bronze 5.1 speaker package......should just about work out at a grand anyway, but you can try other speakers.....
for a couple of grand all in, go to a shop you can demo in like Sevenoaks (or a local hifi dealer) and try various things, personally i can recommend Denon for electronics and Monitor Audio for speakers, however there are a few other makes worth considering....tell them in the shop the kind of stuff you listen to, etc and they can make some recommendations.....oh at this price its also worth haggling either for a small discount for buying a while setup, or if they could chuck on a few cables for free.
then lastly you the 6-10k systems........you definitely wanna be demoing these, Denon, Arcam, Yamaha, Pioneer, are the main names in one box surround amps, but there are other processor/power amp combo makes to consider, speaker wise you got B&W, Monitor Audio, KEF to name but a few.....
.......just remember, if u can, demo it......then you know you like it....altho remember the sound may change a bit once u get it in your home as your home wont be set up like a demo room....