photos looking muted, not bright, on D70

John is certainly correct.  Without samples, it's though to know what you're talking about.

The reality is ALL cameras take drab photos.  The question is, how much processing do you want done in the camera?  A purest would say, none.  For those people, the D70 is doing exactly what it should.  If you're used to the excessive processing that point and shoot cameras do, you'll be disappointed by the D70.  That doesn't mean it's a bad camera.  In fact, it's a very good thing.  It loses less information that way.

If you don't care and just want colorful photos, play with the contrast and saturation in the camera.  You may even want to bump the exposure compensation up a little.  Of course, there's always the one-step fixup in Picasa.