Remote Access on NT

You can set up a VPN connection using either Microsoft's VPN protocols or a proprietary set like Cisco's (requires hardware purchase).
I would suggest a hardware solution such as Cisco's if budgetary concerns allow and cost effectivness can be verified. There are smaller scale units available for the small office solution.
The hardware solution usually includes a basic firewall for added security as you must expose your network to the internet for access thru VPN.
This is a subject that can only be scratched in Q&A and there are reams of information out there on this topic.
Paste
MSKB Q161410
in your browser and that White paper will walk you through the Microsoft setup.
Good Luck

The answer #1 is a very good idea, but if your budget is not so good, why don't you try to use a third part software such as PCAnywhere or Remote Administrator. This is a easy and cheaper solution. About security you can configure your third part software to validate logins depending on IP addresses or passwords security, that's up to you.
If you have the budget and want to give it a try for a VPN ok, but Remote Administrator or PCAnywhere is also a good choise.

Good luck,
@lberto

If security is important, don't use a VPN over the internet. A RAS (Remote Access Server) solution is more secure. Just configure Dial up access for yourself and dial into your server from home. This requires a modem on the server with an analog line and a modem on your home pc. If you setup the RAS connection for dial back you can increase your security by having the server dial back to your home number. So only you can log in and the server dials your house so only that one location can be used to establish a remote connection.
Use VNC software for your remote connection. VNC is free just search the internet for it.

ralph