Just swap it out with the old one....Hook it up the same way, reboot the modem (just to be safe), boot the new PC and you should be good to go (assuming the new PC has ALL the usual default settings, ie., DHCP enabled, TCP/IP stack in place, etc.). Further assuming you're running XP, things should go smnoothly.
You have to REGISTER any new device (router, computer etc.) that you connect to modem at their web site, otherwise once in a while you may lose connection (router or computer may not be able to obtain IP). I had two rouuters, one was being used as a hub. Recently, I decided to change my router - then I started losing connections until I regsitered the router that was not registered yet. You have to do the same if you change the computer that connects to the modem.
You have to go to "sas.r2.attbi.com" and follow the instruction in order to "register" the device connected to the modem.
This is a common isse that I have seen in many post. Please read the following items that I posted earlier
I am posting this for you info, in case you are also using a router, in particular linksys BEFSR41. This sort of problem could be may be due to the router. If you ever change your device that was connected to the modem earlier (router, computer, whatever), you must register it with comcast. See below.
I noticed this problem (losing internet connection on linksys BEFSR41 router) few weeks ago. I found a temporary fix, and did not call comcast or linksys since I don't surf that often.
I have had this router (BEFSR41)for over 4 years (firmware 1.45.7 July 31 2003). Its connected to a RCA modem, supplied by comcast. When the router is powered, it is able to connect to modem and obtain IP automatically. Sometimes during its normal operation it refuses to obtain IP or cannot connect to modem (I don't know which one). To get around it, I had to go to setup/status page on the router, click on "DHCP Release" followed by "DHCP Renew" - then everything starts working (temporarily until same symptoms appear). So this was only a temporary solution.
Today I got a chance to talk to a knowledgeable comcast support person - He said that perhaps my router is not registered! I have two BEFSR router on my network - one of them is connected to modem, the other is used as a hub. A while back, I switched my routers. So yes, that router was not registered with comcast.
You have to go to "sas.r2.attbi.com" page to register your router! If you see something like "you are currently registered to comcast" then your router is registered - otherwise its NOT. Just follow the instructions if its NOT registered.
After registering my router, I haven't had problems (so far).
If this was indeed the problem, then getting a NEW router will not help. Sooner or later, when the router tries to renew IP (some do it every 24 hours) you will notice this problem.
Hope it helps, and I pray that I don't see this problem again. My network has been stable for over 4 years, until this issue.
No there's not.. Most of what you stated is wrong.. Comcast does not care about your router or your PC.. They just want the modem registers.. Everyhing else remains... I have change computers oh 4-6 times (I build my own) and Nic cards more than that.. I have had to call them twice for registration.. Once when I replaced the comcast modem with my 1st cable modem.. and the 2nd when I replaced that cable modem...
You are incorrect. They only care about the MODEM's MAC being registered. It used to be you had to register the devices behind the modem, but that's been done away with. As long as your modem is registered and you do not try to get more IP leases then you are paying for, your're fine.
you do not have to register anything, if you have a new pc then you will have to reset the modem by unplugging for about 5 seconds. the modem is still holding the previous pc's info. after you reset the modem then you can reboot pc or if it is shut down then turn on after modem has acquired its signal. (the light are usually doing what they should when you can connect)