Hey mortimer you are off to a fast start, maybe too fast, I will give you my two cents I am running a sog and have made alot of mistakes, first off I see all your supplies but no mention of tha basics, like something to test the ph in you water, a thermometer to monitor the temp and humidity in your enviorment, if you have them both then great if you dont have either, stop what you are doing and get them both......once you are don with your box, run it for 24 hours and monitor your temperature before you put any plants inside, rule of thumb is intake should be 2-3 times the exhaust, pc fans work fine, and what is the mylay for, your box looks painted white?? Mylar if I remeber correctly is only about 3% more reflective than flat white paint, BUT, it retains more heat..............ok thats enough of my rambling hope some of this helps