my dv4165 i just put a 120 gb hd in it and it works great! being yours is a 4000 series too i would bet it takes an ide hard drive and not serial ata. which would limit you max size to about 320gb i believe? you would think the older technology would be cheaper but they are not i had to pay $50 for 120 gb drive and i did a lot of shopping around on ebay, tiger direct, and newegg, and price watch and thats the best deal i could find. a 320gb serial ata can be had for that price. any way good luck!