Thanks guys and especially for the speedy responses- must be a Nikon user trait

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I will mostly take Landscapes and family so it looks like the 14-24 and 24-70 or the 18-70 (useful range) in the Nikon lenses. I assume the 17-55 in Nikon fit has the same dust issues that the Canon fit had? What about the Tamron 17-50 which is sharp-ish on Canon but on Nikon?
whats the AF-S, non D, AF-D and AF mean?
Whats the Nikon equivalent L lens?
Can I ask anymore questions?

Apologies for so many basic ones but I spent the last year learning everything about Canon but cant find a decent range of sharp lenses at my focal lenghts plus the entry level cameras seem to lag behind Nikon.
I'm looking to get the Nikon D90 if that helps (after cancelling my Jessops order for the Canon 550D)