Digital BW, The Print

Hi,

I'm new to the forum and have just started scanning some of my 35mm 
black and white images (taken on Kodak T400CN).  I like to print 
final results at 11" x 14".  The images so far show 
some "posterization" in them.  I'm not sure of the solution, but I 
think that part of my problem could be in scanning...

Do people generally scan the images at the highest resolution the 
scanner supports with the dimensions of the image the size of the 
negative?  Or is it better to scan at an "appropriate" resolution 
and have the image dimensions be 11" x 14"?

I've been using the latter approach, scanning at 650dpi, setting the 
image size at 11" x 14" and printing at 1440 dpi.

I hope this isn't too silly of a question and I've given enough 
information for a response...

(Technical details: Microtek ArtixScan 4000t scanner, LaserSoft 
Silverfast SE software, Epson 2200 printer.)

Joseph