Yeah, you can use regular PATA HDs on a SATA connector w/ an adapter... I'm using one... I'll be using 2 when I put my new case together and rewire everything. The adapters are about 30 bucks a piece... the one I use is a Vipower VP 9041. Comes w/ a sata cable... I think it's a scam that they try to market it as making your drives faster... Just because you connect your old style HD to an adapter that goes to a fast new technology doesn't make your old drive faster. Ex: Put F1 tires on a Honda Civic.... no performance gain.
But seeing as how Asus poorly designed the original P4C800 Deluxe, I have to do this in order to use RAID w/ non-SATA drives. Still, the sata cables are very neat and small, they don't block airflow in your case.