I'd strongly support Gordon's advice to get your hands on one of the candidates. You know, my wife was quite shocked when she found out how bulky and heavy my new Nikon D80 plus zoom lens was. Carrying something like this around is definitely only for the devoted.
I suggest considering the Panasonic FZ50 (look here for one of Gordon's famous reviews http://www.cameralabs.com/reviews/PanasonicFZ50/
). It's much more "bearable" than any
DSLR! it weighs only 668g incl the super lens. The body of the Nikon D50 is 540g without a lens - a tele-lens adding another 600g!
Plus the FZ50 gives you optical stabilization which is recommended
for shooting telephotos. This is a very upmarket feature that you would otherwise find in the sub 1000$ DSLR segment only with the new Sony A100. PLUS you get an exceptionally flexible 12x tele-zoom build into this smart little camera. This would definitely be a step-up from your current compact plus it's much cheaper than a decent DSLR + super-zoom.
The only drawback in my eyes is the picture quality in low light. This can and will never be the same as with larger sensor DSLRs - although some of them (incl. the Olympus 500) also have weaknesses with low light.
So in my opinion you have to "weigh the weight" of the camera against it's low light abilities and don't forget: if the camera is to bulky for carrying with you, you will miss a lot of nice opportunities to take a pic!
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews
, My Pictures
, My Photography Blog