You know a motherboard is compatable if it says it is compatable. Any of these phrases, Ultra-ATA, PATA, or IDE means its Ultra-ATA. The difference between IDE and SATA is that IDE is parallel, while SATA is not. I have no Idea what this means, but it is agreed on that SATA has a theoretical better max bandwith. This does not matter much, as Ultra-ATA drives will perform almost as well as SATA drives(not including the 10,000 RPM Western Digital Raptor)
The main difference for the end-user will be the cables. Ultra-ATA cables are bulky, and akward, while SATA cables are thin and slim. Performance wise there is no difference, but look,installation,and air flow wise, there is a difference.
6600GT PCI-E for sale/Trade. Check the FS/FT forums on tech-forums for details.