Estimate Server Hardware Requirements

[Usman Sookia]

Hi,

For my current project, I have 10 000 users that may access an e-reporting website (PHP Symfony on Apache, mySQL on Windows) concurrently and I have an SLA which states that every page request should last less than 3 sec. I have pages that access a table of 36 million rows!! For one query executed by 1 user, the best I estimate I could do is 1 sec on my development configuration which is the following --> Os: Windows Server 2003 SP2,RAM: 2 GB, CPU: Pentium 4, 2.80 GHz, HDrive: 80 GB IDE.
How can I estimate the server requirements (memory, processors) for the production environment so that it meets the above SLA? All that I know about the customer is that they plan to use Windows OS on their servers.
Please help!! I could go into real problems if I do not get this right.

Thanks