Network Card bonding has to be done at both the switch and OS/Software level.
It is not something easy nor cheap to do.
Typical switches, routers you buy in stores can not handle such a configuration.
You have to identify your bottleneck before taking this route because if your going out to the internet then bonding 2 10/100 NIC to try and squeeze out more on your 1,2,3 Mbps Cable modem/DSL line isn't going to provide you anymore speed then you already have.
It will end up costing you money in the end