Run Macro if cell value changes auto because another workbook changed ?

I have a workbook (A.xls) and cell(i,j) on that workbook has formula so value on that cell is auto change when another cell on another workbook(B.xls) changed.
i want to run a macro when value on cell(i,j) on workbook A.xls is auto change, plz show me how i can do ?

Hi
Have a look at this link:

http://support.microsoft.com/kb/213612

Good luck.
Tony

Thanks ARGK for reply, but I mean when value on cell is auto change by another application or another workbook, The way you show me maybe run a macro when we take a change by hand on the target, can you show me another way?

anyone can help me ?