I had a similar problem, where my scanner was too 
smart and would automatically sharpen the image 
while saving it. being the photoshop control 
maniac that I am, this annoyed me to no end. 
luckily I've figured out how to opt out of the 
auto sharpening, so everything is cool now. ^_^

jen, it looks like the difference between your 
before and after scans is just a little 
sharpening - you may not need to rescan things, 
just use a good photo editor and sharpen the 
lines a bit. you could also play with the levels.

/Mina