Best way to set up small business server?

[Free]

My wife runs her company out of the house. She is desperately in need of a server that will allow VPN for a couple of users to have remote access. There is one iMac and one PC, with another PC and possibly Mac occasionally connecting, and a couple of iOS devices.

She is currently using a Pogo Plug but it is very unreliable and keeps disconnecting from the network. There aren't huge funds available for setting up a server and it needs to be as simple as possible so that I can maintain it and troubleshoot, with all your guys' help of course. Run a Linux server perhaps?

My wife was asking me about OS X Lion Server but it seems, although I am not sure, that one needs a spare Mac, which she does not have. We have an old Dell that isn't being used but I don't know if I would trust it. It's about 10 years old but I upgraded the CPU, graphics card, RAM, and possibly hard drive or power supply, I don't remember.

I'm not the most tech-savvy guy on the software side of things. I know enough to get myself into trouble.

:help

 

[tim-from-pa]

As much as I built and messed with computers, I will admit that servers and networking (anything outside the computer) is my weakness. However, the Linux would be something to try although I have no experience with servers. I just know that the whole net is based off of Linux so if your problems are say, compatibility issues the Linux would have addressed that as they have to cross all platforms since VPN is software, encryption and such protocols.