Just in case it helps someone else - this is with a late '06 MBP.

Have had several issues with my Airport card over the year plus that I've had my MBP. Though annoying at the time, Apple has solved them all one at a time via software updates.

The latest of which was caused by another Airport update a week or so ago.

The symptom is slow load times - across "all" browsers. And across all wireless connections. And not just slow, more like someone hit pause half the time. The only way to download a page after this pause, was to cancel and then refresh the page. On occasion it had to be done a couple of times.

It seems Apple decided to install the "Airport Base Station Agent" in my Login items. Have not checked to see what this does. Am assuming it looks for an Airport Base Station. Seeing as I don't use an Apple router - I removed this from my Login items, and am now back to the fast load times accomplished with the 10.5.2 fix they managed for my particular card.