Mark, the D50 is an excellent beginner camera and is now at a ridiculously low price. The D70S does offer more in handling and a better frame rate. It has more growth in it, though the D50 picture quality is mind numbing and possibly has even less noise, in some peoples view. With either of these cameras, the only shots that you won't be able to rescue, will be those where you left the lenscap on.
By the way, you are being rooked for the 18-200VR. £489 for mine and arrives next week. This lens is a good one, offering extremely large range, great optics and Vibration Reduction, or Image Stabilisation in Canonspeak. The reviews are all very complimentary and it could well be the "Walk around" lens to die for. Mind you, with Nikons lassitude in getting it into the marketplace, some of us might already have died - of old age.
Conan