For ease of use I have to recommend
SME Server. If my no nothing about computers brother can set it up anyone can have their own server/gateway. I've used Mandrake, RedHat (SME Server is based on) and Debian but for just a simple server/gateway only soulution I use SME Server. I currently have it running on a PII/233 but originally I set it up on a 486/33. Plus it's priced right, free to download the basic setup.
