I don't have the expertise to know at what point spending more money isn't going to do me, as a camera newbie, any good. Any thoughts?"
To this point, don't go *beyond* the Nex-3 or the A33/A35 cameras in price or complexity. The Nex-3 is about $450 and hardly larger than a typical pocket camera, it will be an amazing upgrade from a cell phone, without exploding in physical size. It has interchangeable lenses, although few (and expensive) -- the A33/A35 cameras are similar but take common Alpha Sony/Minolta lenses. Because of the new translucent lenses in this line of cameras, these cameras are significantly smaller than and shoot faster than others in this price range.
So now I'll answer the, "but it is Sony!". Yes, it is true that there is a great distain for all things Sony, and no they are not the market leaders in the SLR space... However, for an unbiased entry-level SLR, the Nex-3 and A33/A35 cameras are an amazing deal... and offer things that others do not for the non-discerning entry-level shooter.