I really am wondering if there is any value in building a computer yourself any more, there are som really cheap deals out there.
if you do NOT really need something in particular there are no "visible" differences between a custom built PC and a pre-assembled one (at first sight).
Otherwise, if you are looking to go for overclock instead you have no real alternatives but buy spare parts then... you really MUST choose every single part to mach what you need to achieve... The most of us just need an average PC with average specs... no more no less...
Gamer PCs must show muscles to go full-frame-rate with the latest titles... so most of those guys are forced to look for a custom build machine even if this means lots-a-money...
Obviously there are many (opposites) POV about it... as an example just try to think about linux users that must carefully pick-up spare components to ensure they can setup/run everything without too much complications.
I'm currently unsing an Intel based notebook with "Mobile Intel(R) 945 Express Chipset" so no pixelshaders frills here... this means I currently can't run many (if not all) of actual prods out there... but i'm still alive, it seems... at least! ;-) ...
[Hey man, wait a minute! What about all of those little inexpensive netbooks? New-Sch00l sceners just consider state of the art HW as platforms to develop for? isn't it bad? why do they do not consider soft-render an option at-all? the audience would be bigger... big audience = big success... or not?!?]