I can only speak for Nikon equipment. I have the D70 and just love it. The D50 is also a good camera, but I would advise to not buy the kit zoom lens of 18-55mm, but instead buy the 18-70mm zoom. The 18-55mm just doesn't have enough range for most shooting situations. For low light shooting I advise the Nikon 50mm F1.8; this is an excellent lens and costs about $100 or less. I like the results I get with the Nikon 5T and 6T close-up lenses on my Nikon 70-210mm zoom lens; when I put both on, I get slightly bigger than 1:1. The 6T is hard to come by right now but Nikon told me this lens should be available again in 30 to 60 days.

Frans Waterlander
pixographer

Hand holding a camera for macro and low light work is the pits. have you tried using a tripod? the same problems may result with any camera you use.

I've got the RebelXT and I absolutely love it. Avoid the kit lens on this one too, though.

And Ronk's absolutely right. A new camera won't improve your low-light macro photography. A tripod will do that, even with your old Optio. Took me years to learn that seemingly simple lesson...

Thanks for the advice! I will definitely try using a tripod more often!