Asus A8N 32-SLI-Deluxe NVIDIA Socket 939 ATX Motherboard/Audio/PCI Express/SLI....

Its specs say that its Front Side Bus is 800MHz or 1000MHz, so can it support a CPU that has 2000MHz Bus? Also, is it good for gaming? cuz i want to put a AMD X2 4800+ on it, and run it for lineage 2.

It supports 1000MHz Hyper Transport (2000 MT/s), so yes it does support the AMD X2 4800+ (socket 939).

Yes, it is good for gaming. Not the best board in the world for overclocking, but it is a stabe board with some nice specs. But the question is, if you are building a NEW system, why 939? I'd recommend going for the AM2 if you are sticking to AMD, or even better, a core duo system.

but

but isn't am2 socket CPUs much more expensive???

Much more? Not at all. About the same in most cases. Where are you shopping?

But again, if you are building a new system, Intel's new core duo lineup is the best CPU on the market now, better than the AM2 CPUs in pretty much every way.