Wireless problem. I have a dell with vista hooked up to a linksys wireless router . This works

Question

I have a dell with vista hooked up to a linksys wireless router . This works alright , but when I try to connect to the wireless router with my dell laptop with a wireless adapter I get connected but I can not get on to the internet . I think the problem is the router because I can get connected and have internet on other free networks . I want to connect to my own network please help !