Before you install and configure SharePoint Server 2007, make sure your servers have the recommended hardware and software. For a small server farm, you need at least one server performing all SharePoint roles and one server acting as a database server. The server computers should meet the following requirements:
Web server and application server Dual-processor computer with processor clock speeds of 2.5 gigahertz (GHz) or higher and a minimum of 2 gigabytes (GB) of RAM.
Database server Dual-processor computer with processor clock speeds of 2.0 GHz or higher and a minimum of 2 GB of RAM.
Field experience shows us that nearly everyone now is purchasing hardware with a minimum of 4 GB of RAM. This amount is preferred and should be considered a best practice in all but the smallest environments.