the 7k1000.C is the new model with 2 x 500gb platters (instead of 3 x 333gb common in older 1TB drives)
xbitlabs has benched it in it's last hd roundup
it's a great drive (for 80 dollars at newegg).
edit: according to someone on the anandtech forum, the E7K1000 has 3 x 334 gb platters...I would certainly not buy that one.
the WD 1tb 7200rpm (1001fals black) has 3 platters also but it is very fast.
check out this article: