This could be a very simple with a macro.
Here's a one line macro that puts in the date/time but doesn't use a
formula (assuming that you know which cell it is going into):

Sub TimeNow()
Range("B10") = now()
End Sub

You could also add a button (from Insert ribbon) that they could click
to run the macro.

On Oct 10, 2:16*pm, Ted wrote:
I have a employee time sheet and let employees punch in/out by pressing
Ctrl+Shift+;. *This works fine but occasionally they punch in wrong time by
manually typing in/out. *Now I am unsing =NOW() with data validation. Only
down side is employees have to press F9 to get a current time. *Is there any
function that will re-calcualte automatically. *I am very new to excel 2007.
I am not familiar with creating a macro. Please help. Thanks.