Toss the Pentax lens you have (sell it, give it away, keep it until it goes mouldy..).

For a new lens, you are a prime candidate for the "kit lens" that each of the three makers offers. So when shopping, you "want" a "body + kit lens". Skip the 20D, as it is more advanced than what you want, need, or know how to use correctly. Sure, it also has full-auto modes, but what a waste for the price!

That leaves the D70 kit, and the *ist-D kit. Visit a camera shop and ask to play with each of them, and totally ignore everything the SALESperson tries to tell you. They're not out to educate or inform, but rather to SELL, thus the term SALESperson.

Pay attention to how easy you find the camera to hold, how quickly it focuses on the intended object in the dimmest part of the store (aim it at dark things.. to simulate a typical home's dim interior).

Take photos with the flash "on", at both the widest angle zoom setting, and the telephoto zoom setting, and then examine the photo to see if the flash left a shadow on the bottom of the frame when shooting wide angle, and to see if the flash actually lit up the subject at all when shooting tele (shoot something 6m or further away).

Don't forget you will also need a 512MB memory card (buy the second most expensive one they have, not the most expensive or cheapest), and you *may* want an extra camera battery.. but you can always get that later, so hold off on the battery for now.

Cheers