compatibility question

i was wondering, my Pentium 4 north wood is getting old and well runs hot. it is in a laptop (fun stuff) and is a Fc-pga 478 i was wondering if i could switch this out with a nice little Pentium-m or such. i need a cooler running system since i am always on it either playing games or running power sucking programs. I've got a dell XPS-M170 and love how the cpu (Pentium-m 2.13 i believe) just glides but i don't wanna take it out since that will void my warranty and i don't feel like doing that all of a sudden. i was hoping some one may be able to aid me in this question, what is the compatibility of taking a Pentium m and swapping it for my Pentium 4. the P4 has a 533 fsb (2.8 ghz) and 512k cache if this might help

thanks alot