If you have the knowledge to do so. Definately build your computer.
Not only can you get more bang for your buck, but you really make it yours when you build it yourself. Especially if you pick out all the components mostly yourself.
No matter how many computers I build, I feel really good the first time I power it on for the very first time, almost like I gave it life.
So yea, if you have the knowledge build it. If not, it's really not hard to learn... especially now adays you just keep plugging wires in until there are none left or all the holes are filled
Good Luck!
PSN: HobsonA
XBL: HobsonA