Need more FW bandwidth on my G5.

Hi guys,

I need to get several iSights connected to my PowerMac G5 for a demo
I'm working on. With three cameras attached, I've exhausted the
bandwidth available on my FW400 ports, so the first camera hands me
640x480 video, while the other two are stepped down automagically by
the iSight driver.

So, It looks like I can only get one full-size video stream per FW400
bus. My FW800 port is not currently in use, and I have three unused
PCI slots.

Can anyone point me to a product that can break out a FW800 port into
multiple FW400 connections, without dragging the whole buss down to
FW400 speed? Also, are there some PCI cards I should look at that can
just give me three or four FW400 ports that don't share their bandwidth?

Ultimately, I want to get as many standard-def cameras as possible
talking to this machine, but getting three or four full-size video
inputs will suffice for my demo.

Thanks,

-jcr