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If you have one of the newer iMacs (updated this year), yes, you can use that adapter. There is also a miniDisplayPort to DVI adapter.

If you have an older iMac (released before 2/2009), you have to use a miniDVI to VGA or DVI adapter.

They are also available on the Online Apple Store.



http://www.apple.com/imac/specs.html
 
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