I know that some (all?) XFX units are made by Seasonic. Still, I'm not sure they retain Seasonic noise characteristics - Jonny Guru has reviewed a number of XFX, you could browse his site to find at least a hint on noise. AFAIK one of the models was v loud. Yeah, I know, JG is not exactly a site to check db, but if they say it's loud then it is seriously loud.
Ok, so here's one I'd be most willing to get for your PC and with your budget
520W Seasonic S12II-520 Bronze - well, its 60 quid, but hey, buy once & cry once
and it sure is a great budget PSU.
Can't seem to find 430W version there, perhaps you could find it elsewhere - this is actually what I can personally recommend as I have one and am v happy with it - it's by no means totally silent, but a v quiet unit at great price. V quiet in idle (100W at the wall for me) and when the PC is stressed my VGA actually drowns out everything else. Don't know how quiet your GTX460 is, but I'd assume you'll first here the card over the PSU.