Changing the format of inches to centimeters in Word 2007

Sometimes, we found  special format writing for a several documents. For example, in typing thesis, each faculty sometimes give different formats.Examples in the Univ. Udayana Department of Mathematics provides a proposal and final task writing format as follows:

Top margin         : 4 cm
Right margin       : 3 cm
Bottom margin   : 3 cm
Left margin         : 4 cm