You are all confused!!
Sata is fastest right now for HDD IDE is older HDD connection, DMA refers tospeed of direct memory acess of HDD, USB and Firewire are external connectors for equipment such as flash drives printers removable HDD, cameras ect...
Current USB is as fast as firewire400 but firewire 800 is faster and E-Sata is almost as fast for Ext HDD as Sata....
Just to put a spanner in works, new USB3.0 will be even faster but still v new and as such not many products out there yet!