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Pretty much what I did last year. Although i never had any intention of selling mine! Keep it and enjoy it for a year. My C2D still does everything I need it for and more (pretty heavy Photoshop etc).
 
I would keep it and get used to OS X over the course of this year.

You could always sell it a year from now and probably lose a lil bit more. Macs have such great reseal value.
 
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