I currently have two routers connected to a cable modem. The second 7-port router is connected to the first 4-port router's port number 4 via WAN. I can get internet to work on the second router fine, but computers connected to the second router cannot "see" computers on the first router under windows networking. Can somebody help me? I'm not sure if this has something to do with a crossover cable or just plain settings. Also, I noticed I have two kinds of cables, CAT 5E and CAT 5. Is one of them a crossover cable?

Cat level has nothing to do with the pinouts that make a cable a crossover or straight thru. E is the newer not newest standard. do a ipconfig or winipcfg [depending on OS version] on the 2nd tier pcs. What is their ip address? Is it the same range as tier one pcs? If so can tier one pcs ping tier two and visaversa? Start with confirming that things work at the protocol level first.

Strange setup. The most likely reason the computers on the second router can not see the computers on the first router is because you have the two connected via the WAN port which means that communication between the first router and the second router is routing and not switching. Netbios (or Netbeui) the protocol used for computers to "see" each other in Windows is not routable. You can enable Netbios to transmit over TCP/IP which is routable by going to network, selecting TCP/IP properties and the Netbios tab. You use a crossover cable when you are connecting like devices. That is a switch to a switch or a computer to a computer. That's because the pins that tx and rx on the cable have to be reversed so that tx on 1 goes to rx on 2 and visa-versa. Cat 5e is the enhanced version of Cat 5. Cat 5e lets you transmit up to 1000 Mbs if the other items in your network are capable of transmitting 1000 Mbs. Cat 5 can transmit at 100 Mbs, as long as the network components in you network are capable of transmitting at 100 Mbs. Else there is no essential difference between Cat 5 and Cat 5 e. Anything using Cat 5 can use Cat 5 e. Mav

Mav is correct. You should connect the two using LAN ports then the second router will just act as a switch (don't use the WAN port). If the LAN side of the second router is in a different subnet, change it to be in the same as the LAN side of the first. If both are acting as DHCP servers, disable one.

Most folks say to disable WEP when setting up two routers (one wireless) like this. Is that not a security risk? Can I enable WEP on my wireless router as long as I also have it enabled on my wireless laptop? If so, how does the router know to allow access to my laptop? I'm thinking this is necessary to prevent someone across the street or driving by from accessing my network.