but this is an extremely biased opinion. if you don't want optimal performance, and don't mind all the advertising built-in to your computer, then a manufactured computer might be for you. most gamers will do fine on an overpriced Dell machine, or if you are into older games a cheaper computer will suit you jsut fine.
just most people prefer a custom computer, that they can learn with and get the most out of. it really is fun, and beneficial to your education. its become a hobby for me, and something i look forward to now rather than dread (i used to hate working on my PC for fear of frying it.)