I dont know if this is the right forum to ask this question :s NO harm trying.

I am looking to setup a new web server (not in my home using port forwarding) in my office where I have to host a mission critical php/mysql application. I have to publish a URL for the customers to login and at a peak time a minimum of 50 to 100 concurrent connections are possible.

Is there any one who can provide a guide or a detailed summary or any input on setting up a new server starting from hardware to the final implementation of the web server. I know security is a big concern and I have a good budget to buy firewalls and IPS module.

I am open to suggestion of what OS and server should be used.

Any help is appreciated.