I'm assuming it's one of the older iPod Video (like the newer generation, Classics) ones.
Click Cancel when it pops up to say erase and sync.
Then, when iTunes is all calm (nothing going on and should see the apple logo up top), do the transfer purchases, if that doesn't work... I'll get back with something you can use.
A program that should do it.
Are these legitimate music downloads, or did you rip/dl them?
Software:
http://thelittleappfactory.com/irip/...FRL4iAodK2Bw2Q