Just recently I talked about Jabber an IM. But now we have Skype. It is P2P telephony which is very well secured. So, download the beta at skyper.net and give me a ring. Calls between computers are for free.
It works best if you use a seperate microphone. If you are in an environment where you cannot talk, skype can be used to send secure instant messages. So, no need for MSN 😉
Edit – check out your local Bruna for a 12,00 Euro headset.