This is the only thing I deplore and what could keep me from buying it. So, I wonder whether the experienced photographer
that you are, could give me some pointers regarding how to deal with that in a professional way.
You flatter me! I'm just a girl taking vacation photos who switched from negative film to digital capture a few months ago. But I've been learning...
The only thing though : the D70 seems to take pictures that are quite cold, poorly saturated and a tad underexposed.
I like the sample images for the eos 300d a lot better.
I'm afraid we're using our camera in different ways, it sounds like. I shoot RAW plus JPG, and, for The Good Ones, convert from RAW using ACR, adjusting as optimal for each image (which takes less than a minute, typically). The JPGs I use only for noncritical uses when I want a "90% there" quicky image without any work, but don't care too much exactly what it looks like. If you don't want to use RAW, though, then I'm not sure what to tell you other than to play with the camera's settings like you've already done.
Yeah, I've noticed that the default settings give you slightly blue (cold) photos - easy to get rid of by adjusting the white balance a little in ACR, but that doesn't help if you don't use ACR.
It's funny - coming from negative film, I find the default saturation settings on the D70 look *quite* saturated to me! It all depends what you're comparing too. (I could also rant for awhile about the current fad for velvia-esque over-saturated photos, but I'll spare you :O )
Regarding your underexposure comment: The appropriate exposure compensation also depends on what you're typically photographing. I find that I'm often dialing in *negative* exposure compensation to avoiding blowing out highlights. That's where RAW comes in really handy - when you're photographing dark forests with patches of bright sky (for example), you can't get a good exposure on the trees without blowing out the sky unless you intentionally underexpose and then adjust things in ACR to get both the shadows and highlights where you want them. I simply wouldn't be able to shoot those images if I only used JPG.
Also I don't think that will fix the problem when I'm shooting RAW.
I'm not sure I completely understand this comment. If you're talking about the cold look, undersaturation, and exposure issues, you most definitely CAN fix them all using RAW and a decent RAW converter (like ACR or C1), for less than a minute an image. You have a *lot* of leeway in all these adjustments (and more) in the converter. However, if it's just a matter of not wanting to spend the time converting RAW files and instead getting images straight out of the camera (which I can understand, though it's not the path I've taken myself), then you might be happier with another camera that gives you JPGs you prefer. If you only want JPG, then it sounds like you've already tried everything in-camera you can.
Sorry about the long rambling comments! Hopefully you found something useful in here.