Dear Michelle A., Picnic and Alpha...
I'm thankful for all this discussion and all the useful data that all of you have provided.

This weekend, I and a close friend have made some test prints with the Epson Stylus Color 740 printer of his, printing a single "hand-made fractal" image of mine.
The image is a 2-bit b/w image, where you can trace some repetitive shapes till they end up as single pixels.
I resampled the image as 72, 150, 300 and 600-ppi images and saved them seperately.
Then, we printed them at 1440-dpi printer resolution.
What I saw was this: the 300-ppi image resolution was the resolution where a "single pixel of the image" appeared as a "single dot of the print" (not as a visible square, thus not as a pixel), and it made no visible difference at a higher image resolution of 600-ppi (other than a smaller image surely).
"Not seeing 'visible squares' in a print in close inspection" is my practical understanding of a "quality print".
Thus, after our test prints, I arrived at this conclusion: for a quality print, the image to be printed must be resampled at an "optimal" of 300-ppi.
Surely, I do not know how all these work for a printer resolution of higher or lower than 1440-dpi...

As for the "max. desired, min. acceptable" resolution of a digital camera...
It appears that the higher the pixel count, the better and/or the larger the image and print...
Yet, the higher the pixel count, the higher the prices...
So, it's obvious to me that knowing my aims must be the single denominator for making a choice of digital camera: for working for the web, 1.3 or so megapix seem to suit very well; for working for high quality and rather large prints (like 20x25 cm [8x10"]), spend the money (if you have that much)..! :)

Well, from all the valuable discussions that I've read here, and from the test prints that we made, I was able to arrive at such humble, simple and practical (I hope) conclusiuns...
They are suitable..?

I'm thankful...