For some reason he contacted me via PM, and I found out it takes an i5 750 to pass the Q9550 according to Anands bench. The lower i3s come close, but they remain a step behind. I know his budget it small and if it gets him going again then great. But I also the those Xeons on Amazon and the 5450 was a lot cheaper. (Might have the name wrong.) $15 for that CPU vs $50 for the 5460.
From what he's said I'm also not sure it's a CPU issue. In my experience boards fail before a CPU will. He talks about not being able to clock his Q9400 high, but it's a G41 board which aren't known for OCing. I'm also not sure I'd trust a G41 to power a 120W Xeon. I suspect there are issues here he hasn't considered.