Hi!
To overclock a t-bird or athlon, your best bet is to do "the pencil trick" (or conductive pen) to unlock the multiplier. Once unlocked, you will be able to run at whatever default speed your particular cpu can reach. You can also select "user defined" in the kt7 softmenu3 bios to specify a multiplier and/or FSB speeds. I have not had much luck increasing my FSB though, anyone else?
So technically, if you are only choosing a different multiplier (and you are stable) then you are still running the cpu/chipset within its specs and I would argue that you are not really overclocking at all. The cpu (multiplier) was chosen to be locked at a particular speed due to price, demand, and stability. Anyway, I think its still generally thought that you are overclocking if you have unlocked your cpu, increased the multiplier, but don't increase the FSB. To make a long story just a little bit longer...
...it will be faster when you overclock on your abit kt7!