How To Set Up A VPN

I have a question I have two seperate networks and I want to set up a VPN so I can connect one network to the other and do a offsite backup. On one network I use a dsl connection to get out to the internet and on the other network I use a cable modem. So Im assuming that the connection would be prity good between the 2 networks. Now my question is how do i connect the 2 networks without knowing a static IP Address they both have dynamic addresses. I thought about using PC Anywhere but I heard that was slow any suggestions on how to set pc anywhere up between 2 dynamic connection thanks.