bcwill,
"wwgmr" is on the right track.
Here's a VBA routine that I've tested (and it works). You can copy it from here, and it of course needs to be assigned to your Check-Box. Right-click and choose "Assign Macro".
Sub ChekBox1_Click()
Dim chek As String
Dim datecell As String
Dim curdate As String
chek = Range("chekcell"

.Value
If chek = True Then
Range("datecell"

.Value = Range("curdate"

.Value
ElseIf chek = False Then
Range("datecell"

.ClearContents
End If
End Sub
The above routine requires that you assign Range Names to these 3 cells:
1) "chekcell" - assign it to the "Cell Link" cell which is referred to when you right-click on the Check Box, and choose "Format Control".
2) "curdate" - assign it to a cell in which you enter the following formula: =TODAY()
3) "datecell" - assign it to the cell where you want the date displayed.
Final Note: The routine has an "ElseIf" condition which will cause the contents of "datecell" to be cleared if the Check-Box is "un-checked". I provided this as an example - if you don't want this option, then simply delete those two rows relating to the "ElseIf".
If you're not familiar with assigning Range Names, it is QUITE simple: 1) Highlight the cell (or range), 2) Hold down <Control> and hit <F3>, 3) Type the name, 4) <Enter>
If you have any problems, I can email you the example file I created. Just email me, and I'll send it by return email.
(Anyone else is also welcome to a copy of the file)
Please advise as to how you make out.
Regards, ...Dale Watson
WORK: dwatson@bsi.gov.mb.ca
HOME: nd.watson@shaw.ca