I have a 3.5 ATA HD inside a macally 3.5 phr-100ac

When transfering files from the 3.5 to a 2.5 FW800 via fw400, i get roughly 25MB/s (not bad, but not great)

hooking the 3.5 up to USB2, and doing the same transfer gets me almost 40MB/s...much better

is the slower fw400 speed because the target disk is on fw(albeit a different 800 port) ???