if your a first time builder and just getting into computers at the same time I would have to disagree with the norm and say that I would definately recommend an intel setup over an amd, for ease of construction and durability.
while amd and via chipsets have come a long way in terms of compatibility, via in my opinion is no where near the level of intel, which basically works with everything.
for example I can use my machine, I currently have a mid size atx case with a power supply that I upgraded a few years ago and paid roughly $100 dollars for it, I know it is still good so I don't really want to shell out another $100 to upgrade it.
I am however considering upgrading my system, my choices are either amd or intel, I know the intel setup will work with all of my other hardware, especially that powersupply without a hitch. However I have questions as to whether or not the Amd setup will work correctly with the PS, video card, and sound card as issues have been raised on this board dealing with incompatibilities. Personally I am tempted to go intel just for piece of mind, I don't have time to research all of my components and I don't have the money to replace the ones that might not work with a new setup.
In my opinion you may pay a litle more for an intel setup but your working with a machine that will just go together easier, and if you do make a mistake there might be room for recourse, what I mean by that is I have seen amd systems toast after a few seconds of someone not plugging in the cpu fan and turning the unit on, granted higher end p3 units may do the same, but I have seen intel cpus that have been working for months with inoperational fan units with only minor errors, and when the fan is plugged in the errors disappear and the cpu works as normal and continue to work, which to me is just amazing.
Choose what you want in the end, but research it first, if your new to this take your time and don't change your mind on a whim be confident before you dive into building the system