Bandwidth planning for MOSS & HW Sizing
Check following articles for guidelines on bandwidth planning & hardware sizing.
Estimate performance and capacity requirements for portal collaboration environments
http://technet2.microsoft.com/Office/en-us/library/a76963dc-1cd0-4aff-ae9c-3736d89c42441033.mspx
Estimate performance and capacity requirements (Office SharePoint Server)
http://technet2.microsoft.com/Office/en-us/library/054526b9-417e-4140-b251-79b68e771c9a1033.mspx
HP have released a Microsoft Office SharePoint Server Sizing and Configuration Tool and test results with MOSS:
http://h71019.www7.hp.com/ActiveAnswers/cache/70675-0-0-0-121.html
http://h71028.www7.hp.com/ERC/downloads/4AA1-1793ENW.pdf
- Refer Page 21 in this PDF : Rules of Thumb