99% of the time it will run fine but at the lower clock so 667 at 533 in your case, it can also cause some kernel problems in some rare instances. Aside from a bios update u will never see the 667, so dont waste ur money, and as far as a bios update dont cross your fingers, laptops are engineered to support the ram speeds it has and for whatever reasons....thermal, bus orbattery issues it is rare if ever that this kind of feature is included in a bios update for a laptop. Im hard pressed to come up w/ just 1 story/laptop this has ever happened to, and even then it was with the old DTR models that used desktop chips while the industry as a whole has moved almost completely to mobile chips.
Long story short, save 20 bucks or so, buy the 533 ram cuz the 667 will never be of any extra bennefit.