Which Intel Core 2 Duo are you talking about? Anyway, have a look at the reviews here:
*www.google.co.in/search?q=Athlon+I...s=org.mozilla:en-US:official&client=firefox-a
Most reviews compare with the Core 2 Duo E7400 with X2 250. I would recommend the X3 405 @ 4.3k over the X2 250. Intel is outdated architecture with the C2D series. No point buying that now. It will give you a headache when upgrading later.