I have a toshiba laptop running XP Sp2 with a dlink dwlG650 air plus. I can connect to my home network via my router OK but when i want to connect outside the house to a open access hotspot I get the 'Limited or no connectivity' message and upon doing the 'repair connection' it is unable to assign an IP address.
I can in my home to my wireless network via wireless adapter.
Sorry, I missed the earlier point about being okay at home.
If you experience problems at cafe hotspots etc best to see if there's a knowledgeable staff member. I was surprised at the help obtained at a local McDonalds -- turned out they used a proxy server and that demanded changes in the user's system.