Record to PC from outdoor camera

[Scott216 <scott.goldthwaite@xxxxxxxxx>]

I want to setup an outdoor security camera that's connected to my PC
via my LAN (could be wired or wifi).
The PC would only record to the hard drive when there is motion so
save disk space. I know they have cameras with motion sensors in them
so the camera only records when there is motion, which would be okay
too, if there isn't too much of a delay.  On the PC I'd set the number
of MB or hours it will store on the hard drive, then the system will
just delete the older video to make room for the new video being
recorded.  Can anyone recommend a system that does this, or point me
in the right direction to build my own.  I prefer Windows XP for the
OS, but I could do it in Linux also.

--Scott