advice on server hardware config to run ESX and ...

Hi there,

I'm planning on buying a new server to run Windows SBS 2008 (primarily for email on Exchange 2007), CentOS + DirectAdmin to host some websites, and Windows or Linux to run game servers (like Counter Strike Source, MOHAA, Quake 3). Does anyone have some advice on what hardware I need to get? Windows SBS needs a minimum of 4GB of memory for example. Should I give every OS it's own HDD and would a RAID config be wise? What processor do I need?

I want to co-locate my server at a hosting company with a 1Gb internet connection.

I hope some one can help me out.

Thanks