Althlon 64 Motherboard w/3GB?

Hi,

I'm planning on putting together an athlon 64 system when I get my tax
return and I'm looking for a good motherboard that will accept 3GB or ram
(or more). I know windows doesn't really allow a program to accessmore than
2GB of ram, but I hear XP pro can access more with certain setup. Either
way, I use a program that will use all 2GB of ram allowed it, so having 3GB
will allow windows to load all of it's bloat outside of that 2GB program
limit. Does that make any sense?

Ok, my real question... I have found motherboards that claim they alow 3GB
of ram, but I've also read that some will not allow you to actually use 3GB
of ram? If they can't use 3GB of ram, why would they allow you to install
3GB? This makes no sense to me.

What I am looking for is a board that supports the Athlon 64 3400, Sata,
onboard Lan, usb 2.0, Firewire, 6 channel sound, etc. Basically all the
bells and whistles. This whole 3GB thing has me a bit confused.

Thanks for any help. Hope this made sense.