In reply to Ben Boldison:
Is it your first SLR? If it is I'd recommend buying nothing more and learning everything about it using the stock lens. 17mm is plenty wide for most landscape stuff, even taking into account the multiplication from cropping. Once you know the camera more, and your style of photography, you'll have a better idea of what you want from your next lens(es). I found I bought lenses early and then realised they weren't the best for me once I learnt more.
If you're experienced with an SLR then obviously forget everything I just said.
For a tripod one with a ball joint is useful. Manfrotto are a rated make. Something like this maybe?
http://bit.ly/bTKNB3
Although not sure how lightweight it is.