Cannot renew IP address of wireless card

HI,
i have a linksys wireless adapter/card, and i have a wireless router at home. Nearly everytime i use my card i get a default IP address for 169.254.XXX.XX, something like that and i cannot access the internet, the icon says that i have good/excellent connection but i cannot connect to the internet.My DHCP is enabled. Other computers at my home, all notebooks, can connect to the router and internet. And when i use the wireless card at the school library too it gives me the same wired 169…. IP address and neither time do i get the DNS servers address. It is annoying and affecting my work.
Please advice how to get rid of this .
thanks