<font color='#000000'>If you just recently purchased your setup and are happy with it and it works just fine, then stay with it as it is. 5.1 is plenty and sufficient for the theater experience. If you are still sitting on an old system of 10 years ago - a ProLogic system, lets say, and upgrading, then its a different story. While some rooms, do to size and geometry will not benefit from a 6.1 or 7.1 receiver, unless you know you will never move or change your room size/configuration, it can make sense to purchase the most flexible receiver you can get. Going to a 7.1 system would give you the option of having 7.1, if or when some 6.1 or 7.1 sources become available; with new recordings comming out in leaps and bounds, who knows. The 7.1 system, running 6.1 material can be beneficial if you have a very W I D E room so the folks sitting on the ends don't have the rear sound comming from thier actual right or left.
It is a bit of marketing push - there is no 7.1 source (or even 6.1 I think) available - but then will a studio put out such soundtracks if there is no player to support it? A chicken-and-egg situation. Of course we can also argue about the need for more speakers - maybe a speaker below or above would be better?
If the software will be there to support 6.1/7.1, ask me in 1.5 years. If you are going to buy a new system regardless - get one thats most flexible; its better to have and not need than need and not have. If you are not in the market for a new system, going from 5.1 to 6/7.1 is not a reason to be in the market - stick with what you have.</font>