I got my cheap mushkin em2 pc6400 2gig kit to over 1000 stable at 2.1v. Ran at that speed for quite a while. Still have them, still work, but I upgraded my server to 4gig corsair dhx. Now they sit on a shelf looking pretty!
And if you want a fast 4gig ocing 1066 kit, mushkin ascent... yes pricey, you get what you pay for!