Ventilation requirements for Precision 3930

I'm looking at putting the Precision 3930 in a 6 RU rack meant for AV equipment which is open on the front and back but completely solid on the sides, top and bottom.  Can I have equipment directly on top of and beneath the server but have the front and back open and still have adequate ventilation ?  It looks as if the fans draw air from the front and exhaust them to the rear so do I need to keep the top/bottom and sides free from obstruction or can I put other equipment directly on top and beneath the server and expect the ventilation from the front to rear be adequate ?