Originally Posted by the grim reefer
I might look into a rug after the tank gets going...
I'm assuming you mean a rug for in front of the tank? If so, then I'm guessing you have hard wood floors or something non-ruglike? You might not want to do that, or at least make sure it's taped down real good so it's not a trip/slip hazard. I can just picture the rug slipping, a person going down, and naturally reaching out to brace/catch themselves against the tank. Maybe I'm just being overcautious, but I moved a clock that was on the wall over our tank because I didn't want it somehow coming down and crashing into the tank. It never has in the 15 years it's been up there, but hey... nothing says it couldn't happen.
Regarding the noise levels, you don't really have to worry about anything else other than your skimmer. It'll drown out all other noises. It's not like they're super loud, buy they aren't quiet either. Next behind the skimmer will be fans on your lights - assuming you get power compacts or something that has built in cooling. If you do get lighting with built in fans, be sure to find them running somewhere in a store and listen to the different brands. Some are noticably louder than others, so if noise is a concern make sure you've heard what it is you're buying.
I was surprised by the additional noise level from my system. But you get used to it. I think of it as my nice little expensive "white noise" generator. Who needs one of those fancy little gadgets from Sharper Image to get your white noise when you can have an aquarium!
About that south facing window - if you don't have blinds on it, or someway to limit the light coming through, you might want to add that before you plop your tank next to it. Much easier to do handywork without the tank there and fear of dropping something on it. Depending on how the sun comes through that window, I'd think you might want the ability to block it out if you need. Not sure of your exact situation, but if you have sun directly beaming into that tank, that could cause you some issues.