ATI TV Wonder has crap picture quality, but is real-time if you use the 7.9 drivers or earlier. I tried several other brands and they had a 1-5 second delay.
If you want to put a domain in your house and have space on the server set aside for users. Then use 2003. If you just want to make the files sharable on the network, xp is fine.
So basicly, if you want each computer to log in through the server to connect to the internet and have hdd space specified to each user 2003 is the way to go.