In playing around with Win500 with a friend, we found that the audio can get delayed significantly if the client computer is not very powerful. In our case, my friend has some ancient Via C3 system with too little RAM to be running XP, but he does it anyway...
When he first connected to me, the first few transmissions were in sync but he steadily and quickly fell behind! By the end of a half hour phone conversation, he was 5 minutes behind!
Even funnier, though, was when he stopped the client. The audio kept playing! Apparently his system was buffering it somewhere internally, and just couldn't play it as fast as it was received. It was rather strange...
I'm not sure if a slow / busy server system would cause any delays. In my case, with a more-than-capable server streaming to my work laptop (XP, Core2Duo Dell) the audio delay is in the milliseconds range, so I'd be looking for things external to Win500 to find the cause of your delay.
A suggestion on finding your external IP: Use something like dyndns.com. You can set up a free account there, and create a domain name of your own (using one of their domains, and a personal identifier - so you could have something like baybum.dyndns.com). Then you run a small program at home (or even better, many router appliances have this function built in) to keep dyndns updated with your current IP. After that, just use the domain name you set up and you don't have to remember the IP or worry about it changing on you.
I just noticed the PM you sent - hopefully you have your questions answered now!
