Demmonnixx is right, the firmware is stored on your ps3's nand (or nor) chip. Basically every time you update your ps3, it saves the state its at and remembers the last firmware update installed. So if you put the 3.00 hard drive in your ps3, it would say you need to install a firmware update of the firmware you currently have installed or later. I once had this same idea too!
But anyway, the best way to go would be to just try fixing the ps3 yourself! I've had (and sold) 5 3.55 ps3s this year just by fixing them with basic knowledge!