Rikazema I have Comcast as well and here is how mine is set up:
Cable in to Comcast modem - Comcast modem to Linsys router / switch ( BEFSR41 is the linksys product) - Linksys to computers
The linksys has 4 ports for computers and a WAN port, the Comcast modem goes to the WAN port. Hope that helps. - J