Connecting clients via VPN

I have remote computers hooked to the internet via DSL. My NT server is also linked to the ISP via DSL. I want to connect the remote clients to my network using VPN. Does anyone know where I can go to figure out how to make the links. I’ve gotten the IP addresses from my ISP for both computers, but they couldn’t help me set it up. They did, however give me a number to a consultant of theirs who would help me out for a fee!!