The video you import may have issues not because of your motherboards, but possibly a conflict in your system somewhere. What are the other components in your PC?
My machine is a quad core Q6600 G0, P5Q Pro mobo, XFX 9800 GTX+ graphics card, 4 MB Gskill DDR2 1066 RAM.
4 SATA HDDs, and a cheap PCI firewire card I bought as a work around this problem.
The PCI firewire card I added is a VIA chip, and it imports video fine.
I don't have another fire wire device to check the fire wire ports with. It is possible that my issue is a conflict with the Sony video camera (DCR-TRV355E) and the Onboard Agere IEEE 1934 controller.