network card trouble

Please help.  I have tried to connect to the internet for 3 days now and have not been able to do anything.  It says acquiring network address for a very long time and then switches to "limited or no connectivity".  I have tried connecting using both my wireless router and by connecting it directly to the Ethernet port, and nothing works.  I contacted my internet provider and they suggested that it was my network card, so I bought a new linksys wireless network card, and spent a good two hours with the tech support people.  They could not get it to work.  I don't know what to do other than pull out my hair.