Ok, my Altec Lansing MX5021's are going a bit...fuzzy. I figure it's best to start looking for some lovely new, shiny speakers. I'm clueless as to 5.1 and what I'll need to link them to my iMac. Recommendations please! My Lansings currently have these specs: SPL 103dB, Front are 20w and the Subwoofer is 50w and a Sig. to noise ratio of >80dB. They have a nice top volume so I don't think I'd need anymore volume, but better quality or equal in a 5.1 system is a must!