Okay kiddos, I think I talked your ears off tonight. Overall, building a system isnt this complex, its just hard to make sure that
A. You don't get an incompatible part, and
B. You don't get a crappy part
If you can't stomach building your own, go buy a PC. Its more expensive, but then again, you have the advantage of being able to yell at someone if something breaks down. I bought from Alienware mainly because if anything goes wrong, reviews say it takes less than an hour to get someone to tell you how to fix it, or pay for you to ship it to them. I'm anal like that, but its all up to you.
In any case, building isn?t hard, either. It just requires skill, patience, and a decent amount of cash. And remember, it'd be super cool to have that computer that can run Half Life 2 at 1600x1200 with AA and AF with all details cranked to their max and not even lag a bit as your pitiful friends cry over their 640x480 crapper.