I'm not to into Intel yet, but just looking on eBay for this chip, this looks like a good deal. Microcenter's E6600 is also on sale right now, but I forget the price.
http://www.microcenter.com/byos/byos_single_product_results.phtml?product_id=243149
http://www.microcenter.com/byos/byos_single_product_results.phtml?product_id=243149