There is another thing you should look for which is the core the chip is made of, sometimes a bios update is needed to support a new core and most companies like HP, Dell and others aren't too worried about releasing bioses to support a new core, so just make sure it is of the same core and 400mhz bus and it should work fine. Also to make sure you can upgrade the cpu at all open the laptop up and see if it is socket or soldered to the mobo(some compact notebooks have soldered cpus) I haven't seen any of these myself but I've heard of them. You can always call or e-mail HP they are more then willing to sell you an overpriced upgrade cpu, you don't have to buy from them but you can get an idea of what are the options available to you based on what they offer you.