I don't want to make you feel like a noob if you aren't and if I'm telling you stuff you already know then I'm sorry, just move on.
Intel CPU's are what we call "quad-pumped". Quad pumped basically means it's the FSB x 4. So a CPU that has a 1066 rating means it runs at 266.5 FSB and an 800 CPU really runs at 200. 1066 and 800 are not the max FSB they are simply the quad pumped number. Typically if you are looking at over clocking you'd be doing good if you could actually get your CPU up to 400mhz actual FSB. If you got up to 400FSB then your quad pumped number would be 1600.
When it says: Supports Intel Core 2 Duo Pentium® & Pentium® D processors with 1066/800MHz FSB. That means you can use processors that run at either 1066 or 800 FSB. These are of course STOCK speeds, over clocking will change that number. Newest processors will even run at 1333 but only if your Mobo supports it.