Split DHCP and DHCP relay?

[kevinadams]

Our DHCP was built out on a single Windows 2k3 VM that is now having trouble.  When it hangs or goes down that means no DHCP for the entire network.  I want to build out a split DHCP scenario but am having trouble with finding instructions for getting our edge switches configured.  We have 3com 5500G or equivilent at the edge of each of our building's subnets.  These use dhcp relay to get addresses for workstations in each network.  In a Cisco router you could have multiple "ip helper" lines and run split DHCP easily.  Can someone explain or point me to documentation about configuring dhcp relay with multiple dhcp servers?

I realize i've been short on details here.  If you need more info to answer, just ask.