I agree with Bama. If you're on a budget, you could do this with a little work of course but airflow will definitely be important here. With all the fans, I would also think that you would want more air pulled out of the case than pulled in (negative pressure) so you don't have stale air sitting in the case waiting to get pushed out. Would help with cooling. The fans on the front typically you would want to pull air in since hot air rises so the lower front fans would pull cool air in and not pull it out. If you have a fan on top, this would help get rid of the hot air and as far as a fan inside the case, it is not unheard of but you would just need to have the space and mount it properly but I don't think you need that here. The rear fan and top fan since these would be drawing air out, you would want a decent CFM rating since you will have other fans on the side pulling air in. In short, from your pictures, I see 2 on the front, 2 on the side, 1 on top, and 1 at the rear. The front and side, pull air in and the top and rear, pull the air out but do it so you pull more air out than you pull in. As long as you don't mind a bit of fan noise, you should be alright.
Personally, I'd get another case. If the Dell mobo is an ATX board, should fit an ATX case that is designed for good setup and airflow and case's are not all that expensive. With that said, if you go that route, do you homework just to make sure the board would indeed fit into a standard ATX case as some manufactures like Dell and Compaq (etc) sometimes do something proprietary where that would not work. I've ran into that before.
Anyway, good luck. It looks like you are on the right track.