CC2500 is 3.3V device.. you may burn by plug on Arduino directly.
you need voltage translator on all in and out signal..
http://www.sparkfun.com/commerce/product_info.php?products_id=8745and also main 3.3v. regulator supply to module too..
Is there a other solution to supply the arduino with 2.4Ghz functionality. We have to communicate with a other device which has a CC2500 chip.