I don't know what size you are printing the final image at, so I can't
comment if the resolution is adequate or not. In general, a file the
resolution you state is good for up to about a 5" x 7" print, or smaller
(about 200 dpi).
You also don't describe what is wrong with the bad prints. Is the color
off, are they blurry or out of focus, or very "grainy" and blotchy? Do
they seem highly pixelated (with obvious square or rectangular jagged
edges on lines and edges)?
Other aspects of file creation can determine quality when printing.
What is the quality of the scanner used? Is it working correctly? Was
it properly focused when the scans were done? How much were the images
compressed (Jpegged), how large are the files on the CD (not once opened
in an image programs, but actually on the disk)? Were the images overly
sharpened?
Was the scanner color managed to supply accurate color files? Is your
system relatively "in control"... what color space was used by the
company that scanned the images, do you have a proper color space
conversion tool to decode it on your computer?
As you can see by my questions, there are quite a number of problems
that can be introduced.
If you have a website you can post a couple of examples of the images
and/or the printer output, I might be able to give you some specific
suggestions.
Art