peer to peer audio/video conferencing advice


I'd like to ask for some qualitative advice on audio/video conferencing. I haven't really found a good simple comparison of the alphabet soup of standards.

One endpoint will be Windows. My endpoint could be Windows or FreeBSD-8.1.

Yahoo Messenger immediately comes to mind as being easy, free, ubiquitous. But the question of security was raised. Not that I need an encrypted tunnel. But rather the client program could be susceptible to unwanted intruders. Trojans, botnets, malware, spyware is definitely not wanted. And the conversation content won't be business or financial or anything requiring protection - just keeping in touch with far-away family.

On my side, I am on a private 192.168 subnet, behind a firewall, with NAT. The public-facing interface is static routeable IP address. This gateway is running FreeBSD-7.2 release currently.

Has anyone got opinions or suggestions about client soft-phones like YM or Ekiga or Skype?
Which audio/video codecs should be used?
SIP versus H.323?
Do I need or might I benefit from a gatekeeper or something like asterisk?
Subjective (or even objective) security threats?

I'd be grateful to hear others' experiences.

Considering there really is no chat software that works with video capture devices under FreeBSD, I have my doubts that your going to get this working. Please let us know how you make out, though.