If you are using MSN or Yahoo you just start an instant message conversation with the other person and then you can invite to view webcam and start voice, the other person does the same and you should have a video conf. Sure you dont need a static IP for these services
The other option is to use Netmeeting (from microsoft), Im sure it will probably be on your PC, but dont have very much experience on that.
There are a few sites out there that have chat rooms for cam users , but be aware there are adult and normal types of rooms.