Zen, why not just hook the modem up to the wireless? Usually wireless ones still allow you to plug at least one ethernet cable in also. For example, I have ethernet throughout the house, so I have the cable modem/box downstairs, hooked up to to the wireless router...and then a cable coming from that hooking it into the house ethernet system. My work computer upstairs is on the ethernet, but the rest of the computers usually just use wireless.

Can't I simply put a new modem on the 4th cable wire and hook the wireless router up to that?

Your cable company would know you have two modems attached. Dunno if that's an issue, as most cable companies let you connect multiple computers to one modem (via a router), right?

You should be able to connect your wireless router to your modem in your office, and then plug your office laptop into the router. Or am I missing something?

eta: Curses! x-post by 6 seconds....

That makes more sense! That means I have to set up the wireless software on my work computer, though, right? Will that leave behind anything that shouldn't be there, or cause me problems when I turn in this laptop and get a new one from work?

That means I have to set up the wireless software on my work computer, though, right?

No. The only thing different from the work computer's point of view is it'll be connected by Ethernet to a network instead of connected to a modem. And maybe that's no difference at all? (It's been so long since I connected a computer directly to a a cable modem.)

That means I have to set up the wireless software on my work computer, though, right?

Nope. I can fiddle with the wireless from my mac wirelessly (...not that I really ever do) and don't have anything of the sort on the work 'puter (which is ethernet)

...you can set up the wireless wirelessly?

All I know, which is very little, is that I already tried to set up the wireless router and it insisted I had a static IP when I don't, and then it wouldn't work, and I gave up in disgust because I couldn't figure out how to fix it. So it's been sitting there blinking uselessly at me for months, and I'm annoyed enough to try again.

Sometimes ISP support will talk you through setting up routers. Varies. But it does not hurt to ask. Also sometimes you can track down a manufacturers support number they will talk you through installation. Sometimes if you catch support on a non--busy time they will talk you through even if official policy is it is not their problem.

My router manufacturer's support was great. I was stunned.

...you can set up the wireless wirelessly?

Um. It's been a while, I don't remember--I might've had to hook up to it once to set it up in the first place. But if I want to change anything NOW, I know I don't have to.

Ok, coax cable from the wall to the cable modem. Ethernet cable from the modem (that you currently have plugged into your work laptop.) now goes into the wireless router (there`s probably a specific port for this). Extra ethernet cable goes from your router to your work laptop.
 
This should get you on, just as before. Now you should be able to call up your router`s admin page on your browser by typing its ip address into your browser. At this point we probably need to know what type of router it is.