u may save cash but i have a frend who did that and found after buying his mother bord he had problems with other compnents.
Always make sure the components are compatible with each other or you will encounter problems. Some can be fixed, unless each products doesn't work with each other.
Also don't forget to type the product name into Google and read a few reviews.
I do recommend building your own computer, as it's cheaper and more likely to work, although if you don't know how a computer works then I suggest you buy a pre-built one. Just please do not go to places like PC World or Curries. Their computers are not very good spec and are not built to run games and the like.
Just a few tips there