Ok, so I got it work now.
On the form, I have Before Insert as:
Me.[WorkOrder#] = Nz(DMax("[WorkOrder#]", "WorkOrders", "[Year] = " & CLng(DatePart("yyyy", Date))), 0) + 1
So now it will start at 2007-0001, and so on. I just want to make sure that this will reset to 2008-0001 once it gets to...