Howdy all! I'm after some advice. I'll soon be getting a thx select capable a/v receiver and I'm looking for some rear speakers for those extra 2 channels in 7.1. However, I'm uncertain as which to go for - dipolar, bipolar or tripolar. Ontop of this they need to be no more than £500, preferably less. So, a few questions. Are dipolar, bipolar or tripolar really needed for 7.1? And which one is preferable? Which make should I go for bearing in mind that I'll probably want to upgrade my current 5.1 speakers? And considering that I'm mainly interested in Home Cinema and SACD/DVD-Audio will they be compatible? I'm a little green when it comes to this, so please bear with me. If anyone can help I'd be most grateful! Ciao!