Assuming your board is 2000HTT it goes like this:
CPU HTT in the BIOS is 200, that's kind of like the FSB on an XP, except of course in your case with the 2500+ you'd see 166 because of it being a 333FSB chip...
Anywho on AMD64's is 2000, and some are 1600, but we're going to focus on 2000 for right now.
CPU HTT = 200
the LDT multi or sometimes seen as Link speed multiplier for a 2000HTT board will be 5x
200x5= 1000, and it being 64bit is 1000x2 = 2000
You DO NOT want the total going above 2000, unlike socket A boards where you'd gain performance from OC'ing the FSB this is not the case.
So assume you OC'd your 64 to 250 HTT, You'd need to lower your LDT (link speed multi) to 4x so
250x4 = 1000 x 2 = 2000 .....still 200 see? if you go well above 250 then you'd have to make it even lower to like 3x.
Memory divider is exactly what it says.....your CPU if given a good one and good mobo can hit like 300HTT+ which not all RAM would hit, so you'd need to then use a divider to keep the RAM running at like 250 or something lower than 300 while your CPU is infact still running at that higher HTT.
That's about it