Nope, L5639 @ 4Ghz doesn't improve much. I tried like crazy to bust 20 seconds.. Never could.. X5650 does it with ease..
stock athlon x4 760k from my brothers new computer for the hell of it
http://i.imgur.com/uivBY3m.png
I'm surprised how mediocre it is
3s slower than my C2Q at 2.5GHz with single channel DDR2 800.