wait so you've already ordered your PC or not yet? if you havent yet, then dont and just buy the parts seperately.
but yeah what huck said is right, im pretty sure they use generic (dodgy) PSU's , they are only good for whats inside when you get it, if you do any upgrades aside from ram and hard drive you would want to change that out for a good brand one (antec, seasonic, corsair)
whats the exact specs of the computer you got? you could always upgrade the video card to something like ATi 5850 or nVidia GTX260, 4GB ram is enough, and change your power supply to say for example Seasonic PSR550 or Corsair HX520