Almost all RAM sold as anything over DDR2 800 is actually 800. When the standard was first certified the speeds were 400, 533, 667 and 800. About a year ago JEDEC added 1066 but very little memory can reach that speed at 1.8v. Buying DDR2 1000 or 1066 or whatever is similar to buying a factory overclocked video card or something like that. The manufacturer is guaranteeing that the RAM will be able to reach a certain speed when overclocked.