*choke*

overkill, ne?  after all, cels are generally 
painted using, what, a dozen colours at best?  
PSP's high-colour image setting is 24 bit (jpeg 
quality), and my happy-nice ATI display adapter 
will only show 32bit. (which is actually also 24 
bit, but tricky.)

which doesn't matter as i've got it set at 16 and 
am perfectly happy with the results.

you might want to read this:

http://www.mustek.com/Class/resol_clrdepth.html

so, start with a lower colour depth.  that may be 
part of your problem.

as for scanning, you're *always* better off to 
scan at a higher res and shrink.  with my Astra 
1600 (love it -- it's a workhorse, and i've never 
experienced any of the scanner woes i hear people 
constantly griping about) i scan at 200 dpi, 
which seems to work very well for cels.  i always 
import directly to PSP, constrast tweak and 
smooth as needed, and resize.  i don't do 
percentages -- since i want everything in my 
gallery to line up squarely i resize to 300 or 
400 pixel height for images, 75 for thumbs.