Buying a PC

Ok I've got about £400 quid and I want a computer that can handle programs like Cubase, FruityLoops and all that stuff and still not chug along at the speed of paint drying. Can anyone give me an idea of the sort of Spec I need to by a PC at. I've already got people that can build me one I just need to know what I need RAM wise, Processor wise, Sound card etc etc...
Cheers anyone

The soundcard will probably cost upwards of £100.

ALSO MATE TRY TO AVOID SOUNDBLASTER

yes, please don't buy a soundblaster!!!

haha- i learnt that from u mark!!!! :lol: