And to provide a counterpoint, dont fall into the trap of believing all the Intel fanboys either. Both companies are more than competant in creating a CPU that will outshine the other.
This process takes time, however, and there will always be a gap where one will have the advantage. Currently Intel has the upper hand, and is likely to remain on top for a while.
The bottom line is that while the K8L could be a Core 2 Duo beater, any of the top line of CPUs will have sufficient power for a few years time, so whatever you buy, it will be able to hold its own for some time to come.