Why is the E6400 available all over the place but the E6600 is only available (for pre-order) through a few vendors? Here are the results from Pricegrabber.
E6400
http://www.pricegrabber.com/search_getprod.php?masterid=22879558&search=BX80557E6400
E6600
http://www.pricegrabber.com/search_getprod.php?masterid=22879556&search=BX80557E6600
E6400
http://www.pricegrabber.com/search_getprod.php?masterid=22879558&search=BX80557E6400
E6600
http://www.pricegrabber.com/search_getprod.php?masterid=22879556&search=BX80557E6600