Connect two Routers to one cable modem

I need configuration data to setup a public and a private network on cable modem that has a dynamic IP.

From everything I've perused it seems like using two routers with different IP's and Subnets where one or the other has a static route (the first in line behind the modem?) OR using three routers is a better way to configure for my needs rather than enabling a DMZ....

I've hit a brick wall mentally and need somebody to give me instruction sans the educational verbiage. I have teenager, a malware illiterate wife, and gamer tenants connected via 802.11 (Linksys WRT310n) to a Comcast dynamic IP cable modem (1 LAN port Arris unit). Everytime I make a change to the WEP it becomes a crisis for all and I get asked to help connect phones, ipads, Mac's, W7 tablet, Vista tablet, and the like. The wife is the only one I am willing to suffer for -I've got an Acronis Image of her W7 tablet on a portable drive that restore from at the point her system has gone completely fubar.

My problem is that I need to access the internet but must be completely isolated from the aforementioned cesspool. I have various routers and switches available - and thought I'd use a Netgear FVS318 for my gear: For current work activity I use a HP tx2 tablet with a W7x64 OS load, which also has a W7x32 OS load with 18 legacy user accounts (old employee profiles). I use an Acer laptop with XP OS and W7 OS that I use for testing various work-flow stuff and re-image frequently.

I've got a legacy Lenovo X60 tablet (XP) that I endeavor to keep off-line and void of upgrades (with the exception of TrendMicro Titanium) as it has 800gig of archive data. I also have a few legacy laptops that run W2k and XP configured for our 2003 domain as well as a couple of desktops with XP, and legacy 2003 primary and secondary domain controller and exchange server racks that connect through an ISA server. I need to avoid making any changes to any of the legacy junk; but need to regularly access info (and via LAN print to a Brother MFC, or transfer to the X60). Hence my need to avoid exposure to the contaminated side of the house.

ISP is Comcast via an Arris modem that is providing the Linksys WRT310n with the default configuration: Internet Connection Data - Automatic Configuration - DHCP (currently): Internet IP, Subnet, Default Gateway, DNS1, DNS2, Domain Name "". The WRT310n has default LAN Data: DHCP Enabled, Router IP, Subnet, Start IP *.1.100, End IP *.1.149, WEP security, No SSID broadcast, MAC filter Access, Qos.

For my internet access - I had been using a Watchgaurd x10 (recently stolen) that had built-in function to run two seperated LAN's. Now I need to go old school and use something I have on hand. If I use the spare Netgear router/VPN/Firewall it is a FVS318 that defaults to DHCP LAN on with subnet Alternatively I have a variety of other 10/100 junk on hand.

QUESTION: Should I use two routers or three? If two routers, should Linksys or Netgear be first behind Comcast modem? Which router needs static route? What should the IP, Gateway, Subnet, and DNS be set to on the static route? and what should the IP, Gateway, Subnet, IP and IP range be set to on the Netgear? A long time ago I think we ran the "public" LAN on 192.168.0.x and the "private" on 10.1.x.x. // I've got a handle on changing the settings on any of this stuff - just need someone to tell me what to set the IP's and Subnets to.

I would really appreciate anyone that can provide me with the data I need to make this work - in a format that "a dog with a note in his mouth" could follow. Thanks in advance from this Dumb-Dog!
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  1. I edited out the public IP for security reason.

    assign IP with Gateway and DNS of to the WAN side of the Netgear.

    then enter into the DMZ to the Linksys

    connect the WAN/Internet port of the Netgear to the LAN port of the Linksys and you will have two independent networks.
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