In my experience it's hit or miss. Word to the wise, if you have all your IDE cables and slots on the motherboard filled with a drive/device, make sure you have an approved Power supply. I had an Athlon 500 with a non approved 250w which died when I upgraded to athlon 800 and added a new HD, I got a 300w Antec powersupply and everything ran fine.
Hope that helped.