Scroll down to the comments - this is where the real meat is :)
1) Map a drive to the share.
2) Run "Sytem Preferences"
3) Select "Accounts"
4)Select the User you want to change by double clicking
5) Click on "Login Items"
6) Drag your share over to the Login Items pane. That will add it.
7) Close "System Preferences".
Double click on your network drive in finder.
Click on your computer name (don't see your computer name?
Finder->Preferences -> under "General" check "Network Shares")
Drag the network drive to the bottom of the list on the sidebar under
the devices category.
That will allow you to save files to your network DRIVE from within
Alternately, if you want to access a specific FOLDER on your network
drive, then drag that folder in the same window to the places category
on the sidebar, and it will then show up on save/open application windows.