The other thing worth investing on, even more importantly than pro lenses (I think so..), is a good, sturdy and easy to use tripod. It needs to be near enough the weight of the camera on it (unless its carbon fibre) and not wobble easily.
If its not easy to set up quickly you'll end up not bothering with it and if its way too heavy you wont bother carrying it at all. The best thing to do is buy an expensive carbon fibre one now with a good head or you'll end up buying a slightly improved one every year or two like me and pay more. I have three or four at home from the cheap and nasty to the fairly solid and for the price of all of them I could have had a top spec one to last a lifetime.
The ones with the brace bar between the legs and the centre shaft are best avoided IME.

Just about any DSLR gives above average results, they also give way below average results if something is set out of its optimum. I've seen some superb stuff from 350D users so stick with it and just try everything that can be fiddled with, especially RAW mode (if you can get the converter!). When I got the D70 first it was a bit of a shock after being used to a fuji that did everything for me (but the way <i>it</i> wanted!) to see dull, washed out, lifeless photos come out of my new gadget. Took about two months of constant use to find out what works and what doesn't before I was in anyway confident of getting useable results.

( BTW some of the rest of the Newcastle photos are here: http://cianmcliam.smugmug.com/gallery/1008980 ). Thanks again for braving the cold and wind and the public transport malfunctions so I could see at least one stone on my trip! It was great to have a bit of company on a stone hunt for a change, I owe you one :)