i agree, be better to get a new one
these cpus are soldered on the mainboard in BGA packaging, if you replace the CPU, you also replace the mainboard which has the north/south bridges as well, even if you do manage to find a mainboard with a higher clock chip, your cooling system in the notebook isn't designed to work with hotter chips. and if you get a BX chipset, you have to replace the ram since the 266 runs on 66Mhz SDRAm, assuming it is unsing SDRAm