Firewire/DV question

This is (hopefully) a fairly simple question:

I take it not all computers (desktops) come out with a Firewire Port ( IEEE 1394) ... I.e. that port where you need to plug in the Firewire cable to connect your digital video camera with your PC.
Can these ports be bought separately and what do I ask for? If so does it come in the form of a card you plug into the motherboard? As I understand it there are also different PIN-size ports (4,6,8,9, etc.) ... Do you need to buy an add-on port for every PIN size or does an add-on card contain all the necessary ports? What kind of empty slot to I need on the motherboard for such an add-on card - should it exist?

I searched a couple of (South African) PC shops for such cards, but couldn't find any, so I suspect that I'm using the wrong terminology or it doesn't exist...

Oh, and while I'm asking questions... I've got a Genie Wonderpro TV card, but it keeps crashing as soon as I launch it. I Have the newest drivers for the card, and I know there was some issues with DirectX 8 and video capturing, but I'm using DirectX 9 so that shouldn't be it. The feeling what I get is that the card isn't compatible with XP. I don't get any response from the tech support. Does anyone have any suggestions about this?

Thanks a lot!
Gem.

You can buy a card that plugs into the mobo. Look at Fry's Outpost.com. As for the other, I have no idea