two pipes one network

Hello all, I need some direction on how to join two internet services for one network so that network resources can be shared.

I have comcast broadband service and bellsouth DSL service coming into our company. I want to segment the network so that I can split up clients to load balance between the two services.

Each of the services(service A and service B) have a linksys router and a 32 port switch. I have 4 servers on segment A and need clients on the B segment to touch resources on the A segment. Currently, I have one PDC on segment A. The linksys routers handel DHCP on their segments.

Can someone please explain the various options I have to accomplish this?