[John_Toolbox]

There are different speeds of PCIe slots, but it's not really going to make a huge difference unless you are using a lot of drives and a very expensive PCIe card. For example, you can put a FW800 card in a PCIe slot, but it's not going to be any faster to connect a single drive to it than it would to connect a single drive to the built in FW800 port on your computer. However if you have 2 FW800 drives, and connect one to the PCIe card, that would be better than connecting 2 FW800 drives to the same port, assuming both drives were going to be reading and writing simultaneously.

Don't get too hung up on having the fastest possible hard drives. You just need to understand what you're buying and how the other components in the chain affect each other so that you don't spend money on something you don't need.