I had a windows XP dell connected to a Motorola modem for Comcast HSI. I later got a Linksys WRT54G. The router is now plugged into the modem and the computer which used to be directly connected to the modem is now connected to the router. I also have another dell desktop with a wireless card. Everything gets on the internet fine, including another laptop. I may need to reinstall windows on the computer directly connected to the router (the same one which used to be directly connected to the modem.) What do I need to do to be sure that the comcast still works after the reinstallation of windows. Also, do I need to reinstall that comcast cd?

Tory,
You do not need to do anything. The comcast info is already in the router(ip address, dhcp info, dns info, etc...). All you will need to do is make a new network connection through windows after the install. No you will not need to run the comcast cd after the install.

That is great, so I don't need to worry about MAC address issues or anything? Also, what is the purpose of the comcast cd?

Also why does their website say this:
Can I use the Comcast High-Speed Internet Service on more than one computer?
Yes, customers with home networks may order additional network addresses in order to connect several computers to the service through one cable modem. In addition, Comcast now offers a Home Networking Package. Click here for more information.

I never had to tell them that I was putting additional computers on, they just worked.

This is the reason that I am hesistant about renistalling windows on this particular computer as this is the one that comcast was originally set up on before I got the router;...back when it was directly connected to the Motorola modem.

Basically comcast is trying to guage you for more money.. All your doing is splitting the same connecting in able to use more then one computer. How illegal is that? It's not.

Now what a router does is it acts as many things but for this concern its basically a wall then the outside world (internet) cant get through. So comcast can't detect any additional computers inside this wall.. Now if you bought a switch or a hub they would detect it and probably send u a letter to stop doing what your doing..

I believe its 5 or 10$ per additional connection.. I don't recommend doing that tho unless you like spending more money..

Reinstalling is ok. Only thing u need to make sure that your tcp/ip settings is set to automatic.

You can either pay Comcast for more IP addresses or use a router to share the one they provide. The amount of bandwidth available on that port is the same wheither you have 1 client or 200 so it doesn't matter to them if you set up a LAN; however sometimes people try to connect directly to the modem through a switch w/o arranging for a 2nd IP Address.

This sometimes works because the ISP usually has a primary IP Address and Secondary IP address set up in case the primary doesn't connect. When the 2nd PC askes for an address the primary is taken so their server assigns the secondary. But it's EITHER/OR: not BOTH. Using both IPs simultaneously is considered Theft of Service and most ISPs will cancel your account as soon as they see it in the logs. A few small ISPs don't care and allow it: Most don't.

So in a nutshell, all I have to do is plug my ethernet back in after the reinstallation of windows and it should work. Do I have to set up a new network connection? And no to the CD, right?

correct!
just plug it in. (it's dhcp by default) and ur router and xp will do the rest..

The only thing you would have to do is if you were sharing files between the 2 computers and wanted them to be in the same work group you would maybe need to change the workgroup name unless you have not

No I do not share any files or printers, just internet connectivity.