Firewire question

[KathyMac!]

I'm running a Beige G3 Tower which I love (it's a workhorse). These were the
last G3s made before USB and Firewire became available as built in ports.
I've since added a USB card which works great.

However, I notice that iMovie "specs" and FCP "specs" on the Apple website
all claim to require a Mac with built in Firewire in order to transfer DV
footage.

My question is simple: Is that completely true? If I added a Firewire card
would it not work fine?

They used to make those claims about USB too..."must be built in ports" but
my USB card has always worked with everything.

Is it more a marketing ploy to get you to upgrade to a new system? My bets
are on the fact that a Firewire card would transfer DV footage just fine but
I wanted to know what others may have learned about that with their own
experiences.

Thanks,
Kathy