Help with linksys wireless connection

I have a desktop computer which my linksys router is connect to with
cable modem, I can access the internet fine on my desktop, however, on
my laptop - which has the linksys wireless 802.11 G nic card- it shows
my signal strength at 100% and the connection to the router from the
laptop can be viewed, but the connection to the internet is grayed out.
I can not access the internet on my laptop but it has connection to the
router. What am I doing wrong? I had to get a new modem from my cable
provider because they updated their system and my modem was no longer
compatible with the new updated system, could it be a setting with the
new modem? Please Help.