Whatever you get get it from Dell purely and simply because anyone else WILL require you to take your broken pc to them at your expense to get it fixed under the years guarantee. Dell will do a home based warranty which, basically, means they will come to you.
I have no connection with Dell whatsoever other than I buy their computers and wouldn't touch anyone elses computers with a bargepole. I also can build my own but I cannot be bothered. Let someone else have the hassle, at least for the first year.