Limited/No Connectivity

I have an Inspiron 1505 with wireless n.  I have had issues with connectivilty since I recieved it.  Initially, my Linksys Wireless B router would not be found, or would only be found after numerous refreshing searches (occasionally would find it right away, however).   I have intermittent connection in which my computer card finds the router and connects, but will not let me connect to the internet.  If I connect with a wire directly to the cable moden, there is no problem.

 

I purchased a DLink rangebooster N router, thinking that perhaps the "b" technology was the problem, but my Inspiron finds the router but never has connectivity to the internet.  I have uninstalled the DLink and plan to return it, but I still have "local access" and "limited connectivity".

 

Suggestions.  BTW, I have Vista Business on the Inspiron.