This is the first gaming PC i am building wanted some advice, first of all i could not decide whether to go with intel or amd here is my amd build although i have not fully decided which one to go with:
It's a bit more, but it's worth the extra £.
There's several things wrong with your build, that mobo needs a prior bios update, that chipset is not good for that cpu(cheap low end micro atx mobo), also a really cheap case, i don't think that it fits the 480 gtx, also the 480 gtx is a card that is power hungry and it reaches really high temps.
A 660 gtx is as good, if not sligthty better than a 480 gtx, but with much less power and heat, and newer features.
Also an i5-3470 is a good cpu, in gaming it's better than the fx, and with a really good mobo.
550w is plenty.