Can't connect on one computer

Ok, a while back I posted a thread asking for help networking my computers. I was told that because my computers used the internet through a router that they were already networked, even though I couldn't figure out how to make them "see" each other. I was given a list of links that didn't help (nothing had anything to do with Vista and that's where we were running into the problem, but as it was not that big of a deal (We just traded files another way) I let it go. We haved added another computer and now I'm having problems that are not something I can just let go. Any help would be sooooo appreciated, as I really have no clue what I'm doing.
*Our main computer is running Windows Vista-Comp1
*Our other "old" computer is running me-Comp2
*The "new" computer is also running me-Comp3
So we get the Comp3 and plug it up to the router and we have internet, we're good to go I think. I was setting up the Comp3 with avg, etc and up pops a box that it has detected my main computer-Comp1 on the network did I want to add a shortcut to the desktop. I click yes, because that's what I wanted all along. I try to open the shortcut and no go, so I decide I'll try and run the network connection wizard. It walks me through it, has me restart, then tells me to run it on the other computer, and restart both computers. So on the other "old" me-Comp2 I do as told. Run the wizard then I restart all three computers. Now the main comp (comp1) pops up with a box asking me what kind of network this is, I chose home, then it "finishes" and asks do I want to view what's attached I do and all my computers are listed-Yay right, nope! All my computers are connected and "seeing" each other, but none of them have internet. So I shut the computers down, reset the modem and router, and start them all back up in the order they are supposed to be. Here's the new problem. Comp1 and Comp2 are fine they are still seeing each other and connected to the internet. However Comp3 Pops up with an error message when restarting (before the logon screen) that says
"The system has detected a conflict for ip address ---(the routers ip address)-- with the system having hardware address --(the routers hardware address)-- The interface has been disabled.
So no internet no connection. I've tried resetting everything and get the same message. I have no clue what to do or how to fix this. But having interent on this comp is a must.
Sorry this was so long, but I wanted to give as much info as possible. My questions are
Can anyone tell me how to fix this? Even as a last resort making my computers not see each other again. Although I would like to keep that if at all possible.
If I upgrade the two ME computers to 2000 (Not sure they can handle much more) will it change this again and give me more grief?

As a side note my AVG on comp3 when it was on the internet, is not able to update through the interent, I've had to download the updates and manually install, even though there is no firewall, any thoughts on that?

Thanks so much for taking the time to read this and maybe to help!!
Tia

 

Ok, not as dumb as I thought but maybe I am, lol I figured out what was wrong. One of the tcp/ip settings wasn't set to get the ip address automatically. So that computer is online again, woo hoo. But main computer comp1 has a differnet workgroup than the other 2 and while comp1 can access all the me computers can only access each other. THey can see comp1 but need a password(no clue what it is) and says it's not authorized. Any clue?

 

OK I think I took care of it my self, but I'm posting what I did in case it'll help someone else. I can't believe how many occurances of that error I got when I googled it. and no solutions posted.
I changed the workgroup names of the 2 ME computers to match the Vista one. Then I went into Vistas networking control center and discovered that pasword protection was on. I turned it off and now I'm able to access Vista computer by all. I think I'm good for now, Until next time...
Good luck and take care