you will only need a BIOS flash if you get an older motherboard that is not already set to go, most today are ready to go. this was much more of an issue when the CPU was brand spanking new, its been our for a while and those issues have mostly been addressed.
intel may need a BIOS flas as well it all depends on the motherboard you chose and the CPU you pair with it.
I suggest you get your parts list together and post back here, we can make sure the parts will work out of the box before you buy anything.