Units for margins

My IE6's Page Set-up uses inches for the margin settings, but my printer (and
everything else on my computer) uses centimeters....If I want the printing to
start halfway down the page, I set it for 6 inches, but then the printing
starts 6 cm.s down. I could set it for the correct centimeter amount (even
though it says inches) and it then prints in the required place, but usually
the required centimeter amount would put it off the page in "inch language",
so the box won't accept the number. How can I make my IE Page Set-Up work in
centimeters?
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Thanks for the help!
Janet