FSB: how to know what FSB is required

hi all, i'm back with a question:

i've bought a PC a couple of months ago, and i turned out the motherboard was broken. No problem there, cause i still had warranty. The problem actually is the fact that my motherboard (ASUS A8V Deluxe) isn't being made anymore, so i had to pick a new one.

After some comparison i choose the ASUS A8N SLI Premium, but they're being delivered with a 1000MHz FSB and a 2000MHz FSB, apparently.
I have an AMD Athlon64 3700+ 2.2GHz and a 2000MHz bus.

Now my question is this: do i have to pick the 2000MHz FSB of the motherboard, or will the 1000MHz be enough, and why?
i'm not very familiar with computer stuff, it's my first pc i've completely created myself.

i know what the FSB does (internal link between the components of your computer). but i'ld like to know if it is important to have the same FSB as my processor.

thanx in advance,
UnrealEd