Big Tim wrote:
...But you're limited by cable length with USB, and they tend to be
"webcams" and not proper outdoor cameras...

Beat me to it Alan.

I've discounted USB cameras and usb capture cards for a number of
reasons, which include:

* Limited length for cable runs unless you include repeaters which
just ups the cost.
* USB tends to be webcams which wont stand up to being situated
outside.
* USB has greater limitations on the amount of data that can be
captured compared to a PCI card.
* I want to distribute the incoming signals around the house so I can
also "watch" the cameras on the nearest TV if I so choose. I can see
who's at the front door by switching channels doing this

What I didn't (forgot) to mention is that the PC that I intend to use
will be up in the loft where all the cat5 and coax will be
terminating. So I'm looking at a 30+ft run of cable for the front
door camera, regardles of system used.

You can get ethernet connected external cameras. You give the camera an
address with RARP and away you go.

There's one used here....

http://library.open.ac.uk/newbuilding/webcam.html