RAS, in it's original sense is strictly modem dial-in. I don't know if they have extended it in Win2k to include PPTP (MS's VPN protocol) or not - Would be logical.
VPN's are kind of a pain to setup and don't always do what you want. For example, many VPN's won't work through a firewall or a router that does NAT. If you work for a big company chances are very slim that you could VPN in. You might, however, be able to use remote control like VNC.
What are you trying to do? Access files? Run programs?
- G