In reply to leroybrown: I only have experience of Canons but I would imagine others will be able to give feedback on Nikons etc.
For that price range I would be tempted to go second hand and £300 is likely to get you a Canon EOS 400d or the slightly older but next range up Canon EOS 30d.
I have owned the 400d and it is a very nice camera and i have used the 30D and as well as owning the 40D and this range of camera is also very good but they are slightly bigger and heavier in weight so the new 400D may be the better option. Both cameras are 1.6x crop cameras which means they will have better reach than full frame cameras for example, a 100mm lens would act like a 160mm lens on a 1.6 crop camera.
When it comes to lenses you could easily spend the same again on a decent lens but here are a lot of good cheaper lenses around. Take a look at this forum to see the types of lenses available and what the users thought of them
http://photography-on-the.net/forum/forumdisplay.php?f=33
If it was me I would be tempted to go for a Sigma 18-125mm or 18_200mm as it is wide enough for landscapes but has the reach for climbing shots. For super wide landscape shots you really need a dedicated lens, something like a 10-20 or 10-22mm lens but they will be expensive (£350-£500).
Even if you buy second hand I would still pop into a camera shop to get a hold of the latest version in the range you are thinking of buying as they will still be a similar size and feel and might help you decide what you want to go for.
Hope this helps a little.
Duncan