Exchange 2003 cluster help

i’ve exchange 2003 enterprise edition running windows 2003 enterprise on Dell server (standalone server, not clustered). i want to make this exchange server as clustered server. i would like to know about the requirements of hardware as well as the help in configuring the exchange accordingly. will i be needing the same type of hardware or it can be different than dell server. also do i need to install the exchange on another 2 new servers or i can make the existing server part of the cluster with one new server. please advise.