Are you able to purchase additional equipment ?
If so, I'd do the following things.
Place the comcast router into bridged mode. Connect this to the Linksys via the WAN port.
Use the Linksys to dhcp serve 10.1.x.x addresses, and to handle your internet connection.
Purchase a cheap switch, perhaps an 8/16 port unit, connect this to the Linksys via a Lan port.
For units that are connected via wireless and a physical port, open the TCP/IP connection properties of the physical NIC and turn off automatic metric, set this metric to 1. Do the same for the wireless NIC and set it to something above 10. More detailed instructions are here : http://www.ezlan.net/metrics.html
Assuming you can NOT purchase additional equipment, then disable DHCP on the linksys, have the comcast do all the dhcp work. You may notice some slowness in the network, this is due to the comcast doing all the heavy lifting.
Good luck, report back and let us know how you go.