yo pong, please don't lash back at me man. I get where got2luvit is coming from! The way you posted made it sound like you hadn't done any research, and wanted others to calculate for you. You asked what you should get, not what brand @ ###CFM. I think he also thought you were being rude when you weren't, and you both had a misunderstanding. I feel/hope that he was only trying to help you out in the future for getting help from us here at RIU! SPREAD THE LOVE MAN!
Also, I COMPLETELY agree with mannurse, as I'm sure FDD2BLK and others would too. I would NOT use the same fan flowing through the dry box then to your rooms. The possibility of spreading mold..how terrifying!!! If anything, I'd put the dry box at the END of the exhaust. I wouldn't even do that though because the air would be hot n humid probably, n' you want nice, dry, n cool!
As for fan recommendation, definitely S&P TD mixvent series. I would go with the TD-150. I have the 100 and 200. The 100 wouldn't be enough, and the 200 would be absolute OVERKILL for a small cab.
HOWEVER if you got the 200, or 200x, you could get away with running a Y-duct to blow through your dry box!
Sorry for the LONG POST. These are just my thoughts and opinions, feel free to get them elsewhere too man! Good luck with your grow, and stay safe!
PEACE.