just FYI (public service announcement) although building a computer can be fun, it can be quite frustrating if it doesn't work straight out of the box.
this is uncommon, but definitely common enough to take into account when buying a new computer (or in parts to assemble)
also, if it starts to play up in the future, by buying in parts, it will be up to you to diagnose the problem and then deal with the warranty of that individual component.
whereas if you buy the computer as a whole, you can (usually) just send it back for their technicians to diagnose and replace the faulty part, whilst it's still within the warranty period.
just wanted to clear things up.
(you've come to a computer enthusiast forum - most, if not all, of us build our own computers)