Hi AQ,
OK. I will admit chatting apps work best between two Macs using iChat if you want fancy video / audio / conferenencing (with OS X 10.4 released Friday £88 !). Apple control both ends of the app, the protocol etc. and it makes for an infinitely better audio / video chat than you can get with any other program. I use Apple's iSight camera. Excellent microphone, focussing. Again, because it is made by Apple it 'plays nicely'.
So, one solution is to get a Mac !
However, I realise this is somewhat backwards wrt the concept of 'chatting with anyone'. I only use iChat to talk to Mac friends as the app is so nice, but I use different systems to chat to other PC people.
Yahoo Messenger is here - they imply Webcam support (though cannot tell if your dad's camera is supported).
MSN Messenger is here - cannot see any comment about video chat support.
Regarding getting things to work. You would both need to check your firewall settings are not blocking traffic. His is in System Preferences / Sharing, and there's possibly another section within his chat apps (though not Apple's iChat, that's seamless. ).
As Apple's system is based on the AOL Internet Messaging framework (called 'AIM') you may both also want to try AOL's chat application. I haven't been down that route.
Windows users download here
Mac users here
I'm sorry I'm not more of a pro-chatter to be able to give further useful advice, but post, and I'll help you if I'm in / around / have anything useful to share !