I just built a Athlon XP system for my son. I put in a Athlon XP 2000 processor. During setup I put the FSB to 166 instead of 133. It boots up and says the processor is an XP 2600. It runs fine. No... it is super fast. Is it ok to do this? Will I have a problem? The chip is not running hot. It has an excellent heatsink and fan. Tell me what ya think.

if all is well leave it alone!

Just make sure you keep an eye on the temps....

My 2600+ is sick I love it! What are his temps? Mine is around 90F

But I get some sick overclocks w/ mine, Im runnin it at 220x11

That should be plenty fine. If you hit stability issues then you know the cause.