Couple of metalink notes for you

Note.156797.1 - What Is The Maximum Memory (RAM) Size Oracle Can Use on MS Windows 2000
Note.225349.1 - Implementing Address Windowing Extensions (AWE) or VLM on Windows Platforms
Note.231159.1 - How to configure Windows to improve performance database oracle
Note.46001.1 - Oracle Database and the Windows NT memory architecture.
Note:46053.1 - Windows NT Memory Architecture Overview
Note:1036312.6 - Utilizing Up to 3GB Virtual Memory on Windows NT