HTIB are about compromises. In order to get all those features for such a good price, compromises have to be made. Less features, cheaper speakers, less power and inferior power supplies, and lack of compatability. Speakers seem to be the biggest compromise in most HTIB systems.
Go for a decent speakers set and a decent A/V receiver. Like Zipper mentioned, Sony does not get much consideration in most Audio/HT forums and there is a reason for this. Look at Yamaha, Denon, Marantz, Onkyo, H/K, and Pioneer. Much better products in terms of reliability, sound and overall quality.
I have never heard the Tannoy speakers you mentioned but I can almost guarantee you they will BLOW AWAY any HTIB speaker set.
I would suggest that you buy the "most" speaker you can. Receivers come and go with new technology. Speakers tend to stand up to time much better. Speaker technology does improve but not nearly as fast as receivers. There are 30 year old speakers that easily hold up to comparison against newer speakers. My father has a pair of old Heil speakers that he will take to his grave with him. I love these things and have been trying to "liberate" them for years now. They are big and ugly but, Oh man, they sound good. Huge bass and nice detailed mids and highs. I love wathing Music DVDs on them.
Shinerman