i might consider waiting for the rumored d90. i have the d80 and love it, though admit that noise can be an issue. however, if you find a good deal (they turn up fairly often in the "for sale" forum at nikoncafe.com), it is an upgrade from what you have. the largest benefit, of course: getting to use primes!
I have a d80 and love it, You will be able to get one for a really good price now the the d90 is around, witch i wouldn't bother with because apart from a few fluff (sales) features there is not much between them.