Charter internet?

I have Charter as my internet provider.
There are two computers in my house: one is a computer that everyone in my family uses, and the other is my wireless laptop, which only I use.
The wierd thing is that I could not access the internet on my laptop even though it is wireless. So, to fix the problem, I got a router so that the internet could be streamed to my laptop as well, but instead, the router (which was hooked to the modem and computer) basically stole the internet from the home computer; highspeed internet worked on only my laptop, and we were left with using dial-up on the home computer.
When we realized what was causing the problem, we decided to get a new router, thinking that it would fix the issue, but, as luck turned out, my laptop could not even detect the weakest of signals. The home computer, however, was back up to speed.
At this point, we called Charter, and they sent someone to check out the problem. Apparently, the guy who came over was not trained to handle

the problem in its entirety, but he did say that (1) my computer was somehow preventing the wireless signal from being transmitted to my laptop, and that we needed the computer to be fixed, and (2) that if we did not want to do that, we could just rent a Charter router, which would solve the problem.
My mother, however, refuses to do the first option, and has been holding off the second.
Now, I'm not sure if I have the regular Charter highspeed internet or the Charter Wireless Home Networking service, but if I have the regular highspeed internet, then what should I do? Which option would be cheaper/efficient: getting the computer fixed, renting a Charter router, or reverting to the Charter Wireless Home Networking service?
Given that I have not had internet connection for quite a few months now, and that I have had to share the computer with three other people (one of which is also an avid internet user, as I am), I would greatly appreciate your help.
Thanks in advance. ;)

I have the same setup. I have Charter cable with a Buffalo wireless 802.11G router.

You hook up the coax cable to the cable modem. Then, a cat5 network cable from the modem to the wireless router. Finally another cat5 network cable from the wireless router to your home computer. (Make sure you are using the correct ports for the incoming and outgoing signals on the router!)

Once that's done you can access the router using the web address that's indicated in the instructions. If I remember correctly it's something like 192.168.1.1, but it may be slightly different. At any rate, this is where you'd set up your wireless network so you can connect using your laptop. Since your laptop already has a wireless adapter built in, once the wireless network is setup you should be able to connect to the Internet.