A reader of my blog mentioned that it’s wasn’t possible to backup to a a share while using Windows Server 2008 backup. Indeed, using the GUI it’s not possible but you can use wbadmin to start a backup to a netwerkshare :
Use the following command : wbadmin start backup –backuptarget:\\fileserver\share –include:C: –vssfull –quiet. (Or add the other drives you wish to backup to this command)