World of hurt.
Either you have the entire library on the network drive, which results in mondo sluggishness as your album artwork is stored there, as well, or
You keep the library local and alias the individual media folders to the network drive. Unfortunately, iTunes cannot save to aliased folders since iTunes 9. Makes adding stuff a ****ed up nightmare.
Or, you use sharing, which won't let you sync iPods/iPhones, won't update playcounts, and and won't let you create/update playlists.
Lose/lose/lose situation.