You will need Windows 2000 or 2003 server (even if it is a workstation class machine). Only the smallest of site can get by with an XP desktop since the operating system limits you to a practical use of only 5 connections.
We provide the free Microsoft SQL Server 2005 Express Edition if you do not already have Microsoft SQL.
Below is a general guideline if you were to set up a new computer for this:
1) Install Windows 2000 or 2003 SERVER (Make sure to assign it a fixed IP address)
2) Install IIS
3) Goto Windows update and do all critical patches
4) Run the installer program from a link that will be mailed to you on request
