Im trying to back up the accounting software on our network. Somebody in the firm is almost always using it for some reason (timesheet, payroll, etc.). Tried Nero and adaptec, both wont allow burning of the files over the network while they are in use. Is there any burning program to do this?

Nahh. Files can't be backed up while being used by another program. I suggest that you schedule a backup time after hours possibly using Nero's automated backup scheduler.