Prepare to be blown away!!!!!! Sadly I can't answer you question and appear clever, but I know a site that can.
As noted above, those are the various surround sound configuration designations. In simple hardware terms, (number of discrete normal range (low-mid-high) speakers).(number bass effect/subwoofer speakers) Blue
The recommendation I can give you is that you DEFINITELY should buy a sound system with a sub woofer, this means (as BlueZannetti stated) sth like X.1. X can be 2,3,4,5,6.. etc, that is your choice! I find my Altec Lansing 2.1 very nice and I am totally satisfied with it the last 5 years edit:// Actually I don't know if you were just asking and don't want to buy, I figured so