dual internet connection setup ?

Hello all

i have a 10mb cable connection and a 16mb adsl connection.

both have their own routers and both are working ok.

what i want to do is to connect both to my network and have them share the internet load.

i have two allied telesyn managed switches on the network and could configure a pc to act as a switch / router if needed.

but what is the best way to do it?

alternativly can i run a seperate lan / wan setup and have some pcs on one wan and others on the other wan but still have them all connected together for file sharing on a seperate lan network?

i have a feeling the latter would get complicated and involve subnet addressing ect

what do you guys think?

thanks

Andy