Quoted from MS Sharepoint Products and Technologies TEAM Blog
The HP ProLiant Sizer for Microsoft Office SharePoint 2007 is a downloadable tool (includes update notification) that assists the user in selecting the optimum HP ProLiant Server, HP BladeSystem and HP Storage configuration for collaboration and document management environments based on user requirements. The tool solicits data or uses built-in defaults to determine the optimum solution, based on the Office SharePoint Server 2007 best-practice configurations and supported growth paths.
The zip contains an executable. Run that and answer a few questions about where to install the tool. The install procedure will first install the SharePoint 2007 sizer, and then the (required) StorageWorks (SAN) sizer which allows the MOSS sizer to generate detailed storage solutions. Once installed, run the SharePoint sizer - that's it.
The sizer includes quick configuration and allows you to do "what if" scenarios. This release includes support for the DL, p-class, c-class, storage, and the latest dual and quad core servers!
Would love to hear your feedback on this tool. Thanks HP, especially Jimi Ibbett from the HP Engineering team for such a useful tool to help customers with their deployments!
You can download this free tool by going to the SharePoint Active Answers page on the right hand side under Sizers and clicking on "Microsoft Office SharePoint Server Sizing and Configuration Tool" and logging in. (You will need to create a free account if you haven't.)