A dell has as much, if not more chance of breaking than one you build yourself.
"but dell is a huge company, surely they must use good parts!"
Hah, dell uses the cheapest junk they can get their hands on. And unless you shell out the extra 100-200 bucks for the good warranty, i think they only come with 90 days warranty. So do yourself a favor, build your own, get a much better machine for the same amount of money and know that you got all quality parts because you picked them out yourself.
Also, dont call me shirley.