You will ahve to check the revision level of your board to see what type of processor it can run.
As listen on abit's site: 4. Does ABIT KG7 / KT7A / KT7E mainboard support AMD Athlon XP processors?
Statement: ABIT KG7 / KG7-RAID mainboard is hardware compatible (ready) and can support AMD Athlon XP processor via BIOS update.
ABIT KT7A / KT7A-RAID V1.3 mainboard is hardware compatible (ready) and can support AMD Athlon XP processor via BIOS update.
ABIT KT7 / KT7-RAID / KT7E all version and KT7A/KT7A-RAID V1.0/1.1/1.2 cannot support AMD Athlon XP processor.
ABIT has release BIOS for KG7 and KT7A V1.3 to patch the CPU model name. If user did not upgrade to the latest bios, users can also manually set the suitable working frequency for AMD Athlon XP processors in SoftMenu BIOS.
AMD Athlon XP Processors SoftMenu III Setup -> CPU Operating Speed ->User Define
With above setting users can use AMD Athlon XP processors flawlessly. The incorrect CPU information during POST can be fix via BIOS update.
As for KT7 and KT7A old version mainboards, which launched earlier than AMD Athlon XP processors, they are not hardware compatible with new CPU.
In other words, if you have revision 1.3 you are good to go, anything other then that and you will have to get a new mobo to run a xp chip. Oh, and the fastest chip that you can run on it (if it is not a rev.3) is a 1.4 thunderbird. Goodluck!