I woulda say the first one, the 64-bit. It should be about the same speed while it is 64bit so when Windows 64 comes out you will be able to utilize the benefits of 64bit architecture which i read are projected to be around 20% increase in overall performance. While not the latest cpu and already slightly dated because of its socket 754 and core. It is still a good processor, you may not be able to oc it as much as the Barton but it will be better for the future.