What power supply to use

Your SB5120 is not a wireless device. I think that you are confusing the cable modem with the wireless router. New modems may have a wireless feature.
I assume that your modem is hooked up to a router that has a wireless feature and you are trying to set up or re-set the WEP encryption key.
Try searching for a manual under the router name.
You can always bring the router back to its original default state by pushing the re-set button, located on the back of the device. It is usually a small hole about the size of a paper clip near the on-off button. While the router is powered on, push the point of a pen into the hole for about 10 second. Then you can go through the router menu and reset all the passwords, WEP keys and other parameters.
If you need help on how to access or set up the router menu, please comment. Also let me know if this information helped you.
J

You should be able to just unplug the usb and connect the Ethernet cable to the netgear router without any problems.
Thanks,
Robert

THIS ROUTER SUPPORTS CAT 5 CABLE

So you will need a modem that supports CAT 5

Regards
TOM

Motorola SB5120
The Motorola SB5120 SURFboard® is a very popular, solid and reliable cable modem compatible with most cable providers. If your modem is two years or older, upgrading to the SB5120 has been known to show speed improvements up to 3X faster than older DOCSIS 1.0 modems. Set up is simple and fast.

• Compact design: With its attractive and compact design, this cable modem won't clutter up your work space
• Easy to maintain: Simplify troubleshooting with the handy font-panel LEDs and built-in HTML-based diagnostics
• Stand-by switch: Disconnect the signal without unplugging the modem with the top-mounted stand-by switch
• DOCSIS™ 2.0: Take advantage of DOCSIS 2.0 technology for up to three times greater upstream capabilities than older modems running on DOCSIS 1.1

Linksys BEFCMU10
Quick to set up at a great price, the Linksys BEFCMU10 offers fast connections to your cable broadband provider. Connect it directly to any PC with an available USB or Ethernet port, and you're ready to surf the Internet. With the Linksys Cable Modem, you'll avoid monthly rent charges, and make the most of your high-speed cable Internet connection.

• Compliant with all industry standards: DOCSIS™ 1.0, 1.1, and 2.0 - compatible with any cable Internet provider
• Ports: Ethernet, USB & Cable
• Buttons: Reset
• LED Indicators: Power, Internet Cable, Internet Activity, Ethernet & USB
• Easy installation: One phone call to your Internet service provider completes the setup

D-Link DCM-202
D-Link's DCM-202 Cable Modem is powered by TurboDOX™ bandwidth acceleration software increasing your download speeds up to 20 times. The DCM-202 makes your broadband connection more efficient and effective by clearing network congestion, resulting in a boost in download speeds. With the DCM-202, you will get more out of your broadband connection with increased bandwidth and enhanced performance.

• Always On, Always Connected
• DOCSIS™ 2.0 Certified
• Ethernet or USB Connectivity

Wireless Routers
Netgear WGT624 Super G 108 Mbps Wireless Router Netgear's WGT624 108 Mbps Wireless Firewall Router is 10 times faster than 802.11b routers providing 4x the range of 802.11b devices, and double the range of most other 802.11g products. Your home network is secure with over 10 security and privacy features including a double firewall and wireless encryption. Netgear's Smart Wizard set up software gets you connected in 5 clicks or less!

• Interoperable with existing 802.11b and 802.11g networks
• Smart Wizard gets you up and running in fewer than five clicks
• Lighted power, test, Internet, wireless and LAN status icons
• Works with most Internet gaming applications that support Universal Plug and Play

Take the ethernet cable which is going from your Warner cable modem to your computer, and run it from your cable modem to the input connection of your router. Then take a second ethernet cable and run it from the router (ports 1, 2,3 or 4) to your computer. Log into your router's setup page (see your instruction manual), and set up all the passwords and wireless settings. Please read the instructions for specifics of your particular router.

the sb5120 does not have a reset button- you just unplug the power cord and plug it back in to reboot it, it is a modem not a router. click start-run- type: cmd and click ok then a black box will come up and type in: ipconfig and press enter and that should give you your ipaddress of your router if you are connected through a router

YOU WILL NEED TO GET A WIRELESS ROUTER TO BE ABLE TO USE THE LAPTOP WIRELESS, iT IS A VERY EASY SET UP AND CONNECT THE DESKTOP WIRED AND THE LAPTOP WIRELESS TO A WIRELESS ROUTER.

are you sure your hooking the comcast modem in the right place?

You can still use your existing Linksys router with your cable modem. In fact the router your have is designed to work with DSL/Cable Broadband connections.

1. Make sure to properly connec the devices in your network. Modem will be connected to the Internet port of the router. Then, laptop will be connected to one of the 4 Ethernet ports of the router. For initial setup of your router with modem, you need to hardwire laptop to the router.
2. Press and hold reset at the back of the router for about 15 seconds.
3. After 15 seconds turn off the router and then turn off the modem. Wait for a minute.
4. Power on modem and wait for the lights to be ready.
5. When modem lights are on, turn on router.
6. There should be 4 lights on. Power should be steady green. Internet, WLAN and Ethernet port.
7. Checked if you have Internet connectivity on your laptop while it is wired to the router.
8. If Internet is working, disconnect laptop from wired connection to the router and check available wireless network that laptop can detect.
9. The default wireless network name that the Linksys router broadcasts is "linksys". Connect to it which is an unsecured wireless network.
10. Once you are successfully connected, check Internet.

Hope this helps!

Plug your cable line into your modem, make sure it's tight, but don't use a tool. Next plug the ethernet line from the modem to your PC ethernet port. Then plug in your power to the modem. Allow your modem to sync. Don't use the USB line at all. Do not even hook it up unless your computer doesn't have a working ethernet line. Don't run the disk either, it will only install the modem driver that is only used if you use USB.

If you have issues connecting after that, you may have to go into your ethernet adapter settings and make sure that it is using DHCP. DSL usually uses a different setting (PPP I think) and you will not be able to connect.

By the way, excellent choice in modems.