If you went to richersounds you could get the sony amp and kef speakers for £450, I asked my local richersounds today about the Sony, he recommended the Onkyo Tx-SR505, currently the same price as the sony, although the sony has been discounted.
For an extra £50 you could go for the KEF KHT 2005.2 from play.com. I heard this setup the other week at my girlfriends parents house. Impressive, absolutly Huge sound, although his setting up of the kit wasn't great, the front 3 speakers were all on the TV stand and the rears were on the floor, but its a package im very very tempted with!