When I first got my Pi I also got a PiFace. My first try with Piface was pretty disastrous. I thought the whole point of relays is that you can use a separate power source for your motors? So I attached a battery that was too powerful for Piface and Pi and both were fried. I should dig them both out as there's gonna be loads of recyclables in them. So pleased that they are relativly inexpencive.
Piface which stands for 'Raspberry PI interFACE', is probably more useful than I have indicated, I should have read the instructions. PiFace fits directly on top of Raspberry Pi via the GPIO interface. GPIO stands for General Purpose Input Output.