VPN Setup

I have a client that wants to allow his employees to log-in from home. His work network is a ‘File & Printer Sharing’ network with no servers. They use a LinkSys Router/Gateway for internet access at work.

He wants a firewall to prevent unauthorized access. I’m thinking a hardware box at work and a software solution for the home computers. He does not want to pay for a box at each employees home.
I’m also thinking to move everyone to a file server. I’m not sure if I can get everyone to the right work computer from home using ‘File & Printer Sharing’.

He will have no more than 10 employees logging in from home.