Those lenses are not very exciting, and you'll lack wide range.
If you decide to keep them, I'd rather go for a used D50 or D70 ($400 in excellent condition with the accessories), to be able to autofocus. The D70s costs a bit more.
If you decide to sell them, a new D50 with 18-55 and 55-200 AFS will cost you around $600 (no VR).
Personally, I prefer a used D50, D70 or D70s to a D40 (and maybe even to D40x and D60). You can always sell your lenses later and maybe spend a bit more on a Sigma 18-200 OS, if the Nikon 18-200 VR is too expensive for you.
I think it's mainly a question of wanting a camera with more than a couple months of warranty. If this is the case, your cheapest option would be the D40 and I would get rid of those lenses.
The D70 can die with BGLOD, but Nikon would fix this even when out of warranty (at least in some countries and when official import).