I tried to save a little money by upgrading my system with Firewire and USB 2.0. I bought the Adaptec Duo Connect and it worked great--for everything except video. The USB 2.0 works like a champ, but the OHCI 1394 kept dropping frames on video output. I even got dropped frames importing a 20 minute video from my Sony PC-9 Camera. I shut down every process including the sys tray and the results were marginally better, but still, dropped frames plagued me.
I bought the ADS Pyro here at VideoGuys and it showed up today. I plugged it in and viola! NO MORE DROPPED FRAMES!
Equipment DOES make a difference.
BTW, I am running both cards in the machine with no apparent side-effects. I still get my USB 2.0 and now I have more fire-wire ports than I know what to do with!