Probleme connecting to internet with my new comput

[Hedos]

Hi, I bought a new computer one week ago. Now I'm trying to create a network to allow my 2 computers to have internet access.
I bought a switch with the nessessary cables.

Both computer have Windows XP Pro.

My new computer doesn't seem to be able to connect to internet via the switch. So I tried to connect it directly to the modem.. but it does not even work.

I know my switch and my modem are not faulty, my other computer can connect to Internet perfectly via the switch or just directly connected to the modem.

I also know that the network card on my new computer is not faulty...
A few days ago, I was using a wireless network with a wireless router and a USB network adaptater.. everything was working fine on both computer. During that time, I also plugged my new computer to my router with a network cable to transfer some files... ( This means that my network card is not faulty )
(now I returned back the wireless network and I bought a switch with network cables)

Now I don't understand why my connexion is not working. I tried a lot of configuration but it never works.
When I try to open a web page or MSN Messenger, a message directly appear, with no delay, telling me that no internet connexion was detected...

My connection, 'Local Area Connection' is enabled.
Obtain an IP adress, DNS, etc.. is all set to automatic.

I don't see what is wrong :/

Someone have an idea of what should I do?
Thanks

 

[sturm]

if you only bought a switch then there is the problem. Switches dont give out ip addresses.
Run ipconfig on all computers and make sure that they dont have the same IP.
What you need to do is get a router. That will give out seperate IP addresses to each computer on the network.
You also may need to change some settings in the internet options.

Write back what you get off the ipconfig results and we will go from there