I had been thinking about upgrading for a couple days - even though I didn't really -need- to. I saw 4GB PC3-8500 1066MHz RAM for $19.99 each, but my local Best Buy had 2x4GB PNY PC3-10666 1333MHz RAM for $41.99, I figured if it didn't work I'd just bring it back. Works great! Shows up as 1333MHz, too. Sure beats ordering from NewEgg or Amazon and then waiting for it to show up, even if it cost a buck more.