you'll need some venting in that room, even though it is in the basement - dual 400's can be pretty hot yes, but people have gotten around that problem. I think Brad runs 400 Radiums on m59's, and over a 75 gallon.
you could also suspend the canopy for a bit of help with airflow:
that's 2 - 400W over a 110, with a stand fan on "low" blowing across the tank top. it stayed pretty cool, in the basement.