Grow room ventalation-new house

I finally bousht a house in florida and am chasing my dreams of a Grow room, I have a 400w HPS and a GrowBright 4" Inline Fan comming tomorrow, I WAS thinking about venting into the attic until I read alot about mold and dry rot. The humidity is usually pretty high here in florida so im not sure how much the humidity from venting into the attic will matter. I have read about venting throug the soffit but my neighbors house is pretty close so i dunno if noise will be an issue. Unfortunaly the joining bathroom has no fart fan to use that exhaust.

Anyone got any pointers or suggestions? I will be greatly appreciative.

Also I'm gonna have to vent into the attic for a couple of months until I get enough cash to finish it compleatly, I hope a temp vent to the attic won't hurt.

If you vent outside and the neighbors are close then hook a carbon scrubber into the vent fan

With one 400 w HPS you aren't going to be growing a crop large enough to alert the neighbors if you vent out a covered window.

I have a 4" growbright carbon filter jr.http://www.htgsupply.com/viewproduct.asp?productID=49749 allready. I hope this is sufficient. And its in a walk in closet the area is gonna be about 4'w x4'd x8'h