Yeah --most newer/better-quality Mobos configure "jumper settings" in the bios these days-- for a basic build-- you would not need to change anything right away.
I found this site in 2 sec google search...
http://www.pcmech.com/byopc/
it really is within the realm of possiblity to build your own PC -- I've done it several times now-- 6 years ago I didn't know how to turn one on.
The big issue with building your own is NOT assembling the machine-- it's the software you already own. If it's a FULL version of :
Windows-- you OWN the software (not a recovery disc)
Your favorite Firewall?
Your AntiVirus?
Your Office apps (Word-- whatever)
any other favorite apps that came WITH your old PC-- you can save that money-- you don't need to buy it again.
While Newegg is one of the BEST places online to buy hardware... you need to thoroughly research EXACTLY what you get with all your hardware-- if you buy everything through them. BEFORE you buy.
If you need a retail version of WIN XP--would they throw it in as part of a "package deal" ? Same with any other paid software.
If you already own the full-versions of all this there's no sense in buying a PC off-the-shelf with preintalled versions of all that on it.
Commercial machines today often come with a buch of stuff that:
a) you don't like,want,or need
b) are only 'trial versions' --so when you get used o it-- a window pops up saying basically "now you have to pay for this-- or it'll stop working" or some other extortionist tactic.
With a few hours of preparation / research-- you can have a beautiful/stable/long-lasting PC... that you now have the confidence to upgrade/troubleshoot/fix yourself-- that will save you a few bucks now-- and maybe MANY down the road-- because you'll be starting off with better-quality hardware NOW-- and installing EXACTLY what YOU want on it and NOTHING MORE.
<<< YOU CAN DO THIS>>>