Is it possible to have the checkbox value (either checked or unchecked)
dependent on if the number in another cell is positive or negative (greater
than or less than zero)?

I've tried the "cell link" option on the "control" tab of the format control
popup menu, but it doesn't return what I want. It seems to do the opposite.
It takes the value of the checkbox and returns a true or false in the linked
cell. Is there a way to reverse it?

I'm using this on an expense voucher form and the checkbox indicates if the
final balance due (after deducting any advanced monies) is payable to the
company (negative balance) or payable to the employee (positive balance).

Any help is appreciated. Using Excel 2002 with Windows XP Professional.