Agreed go with the X3, if you pair it with a decent MSI board you can OC it very easily with just a little switch on the mobo, to more than make up for the 100mhz deficit.
MSI 880GM-E43, AMD 880G, S AM3, PCI-E 2.0, DDR3 1600, SATA 3Gb/s, SATA RAID, mATX, VGA, Unlocked CPU