Implementaion of VPN

I am in the process of helping a friend reduce the cost of connection a remote office with the main office accross the country. Right now he tells me that he only has two computers that he needs to be connected, however, in the near future he plansto connect three additional computers. At present the connection is being done with a dialup and the long distance cost are getting out of hand. I believe he has about a $5000.00 budget. The security issue is about a 4 on a 1 to 10 scale. I suggested a simple VPN, although, I’m wondering if that’s not an oxymoron. I’m not sure if it would be faster to contract out the VPN portion or setup a Windows 2k server with that service. Any suggestion would be greatly appreciated.

Ron