You need file server management MMC > Right click shared folders > all tasks > configure shadow copies. That is on a normal setup at least. I think you have some confusion somewhere though because the shadow copy has nothing to do with the recycler. This maybe some Viglen thing your dealing with.
This isn't Shadow Copy.
Shadow copy is the Previous Versions tab you get from the Properties option of the right click menu.
If you're using that you could turn the Recycle Bin off for users, this would be done in Group Policy (I'll find where in a bit).
Remember though that the advantage of the recycle bin is they can get accidental deletions back that they did since the Shadow Copies were last made.
Incidentally, if you use Mapped Drives items aren't sent to the Recycle Bin at all, only if they're deleted be going through My Documents.
Is it possible to set a GPO to empty the recycle bin at log off? This would help me a lot :)
User Configuration - Administrative Tools - Windows Components - Windows Explorer
There you have the option of stopping things going to the Recycle Bin or you can just limit the size it can get to which will probably be up your street.
There isn't one to empty it.
We don't use the recycle bin... just Previous Versions