OT: server equipment to choose

[Strong]

I have to project a web/db-server that should handle 1,000
simultaneous users. So, I would ask an advice on its hardware
configuration and software to use.

1. My guess is this 2 servers of the following configuration:

2 4-core xeon 5335 CPU with supermicro case + sopressmicro mb + 4x4Gb
RAM kingstone dual full buffered + 5х140Gb SCSI fujitsu HDD + SCSI
adaptec asr-3805 raid5 controller

organized together as a cluster.

2. OS I think to use last RHEL (or CentOS is good enough for this?)

Please share Your opinions on this specifications - whether it is
suitable for such a task?

Sorry for OT and thank You for Your answers.