OK to start off with, if your listed system is still correct you're running a core2duo e8400 which doesn't put out a massive amount of heat or need a massively high end cooler.
So I'd say a coolermaster hyper 212 plus
http://www.scan.co.uk/products/coole...m2-am2plus-am3
for £20 it's easily the best low cost cooler in the £20 or less price range, if you correctly setup the PWM settings in your BIOS it will be slient.
I copes very well on my i5 750 with the fan at a silent 860rpm when idle
Unfortunately it's not quiet enough to get the free shipping from scan so you might want to consider Play.com instead
http://www.play.com/PC/PCs/4-/117187...k/Product.html slightly more but with free postage it's actually slightly less.