AnandTech has a nice post up about the Intel E8500 Wolfdale processor, which promises to be an even better overclocker than the E8400. Back in the day, hardware enthusiasts would pick a CPU that was at or near the bottom of the line speed-wise for a processor family, and then increase the front-side bus speed in order to over-clock the CPU, often by 50% or more.
Now, it is starting to make more sense from a performance perspective to pick a CPU with a higher multiplier, and then be able to get a higher over-clock at the same FSB speed. It turns out that many motherboards are running into limits in how much you can increase the FSB. Similiar limits often show up with RAM.
This is why an E8500 with a 9.5X multiplier may be better than an E8400 with a 9X multiplier (especially since they both probably have a similar upper speed limit for the CPU). Right now, the best bang for the buck for general purpose computing is the soon to be discontinued Q6600 Quad-core Core2, which runs at 2.4GHz, and is available at Micro Center for $199.00.