connecting to Active Directory over the internet without VPN

Hi,

I'd like to know if it's possible to connect to an Active Directory over the
clear through the internet via dial-up.

The configuration I'm aiming for works something like this:
1. Remote computer (i.e. a laptop in an isolated area) is powered up.
2. User logs in at XP login like they would if their PC was in a local
active directory domain.
3. Laptop dials up to a ISP through the modem and connects to an active
directory server that's on the Internet, in the clear with no VPN tunneling.
4. Active directory validates user on the laptop and allows user to log in
if the user is valid.