Purchasing a CPU with the specific
intention of over-clocking it is about like buying a bicycle with the
intention of turning it into a motorcycle by strapping an engine onto the
frame.
In short, I would not recommend purchasing any CPU just to over-clock
it. CPU over-clocking can, in some cases, permanently damage your
processor.
If a 600MHz CPU is what you need, you should buy a
600MHz CPU. And in that case, an Athlon
600MHz is a good choice these days. It may cost twice what a 400MHz system
now commands, but will come equipped with a higher speed bus, memory, and
motherboard components that will provide an upgrade path that will last
longer into the future.
In most cases, over-clocking an older CPU to squeeze some more useful
life out of it can be achieved successively. Just make sure you provide
adequate cooling and check your motherboard settings carefully before
booting up. However, there is no guarantee that a new CPU will tolerate
being reliably over-clocked to the speed you really want.
That being said, Intel's Celeron line
has been shown to withstand the stress of over-clocking better than AMD's
K6 processors.
But do so at your own risk!
For more information on over-clocking, check out these Over-Clocking
Guides...
