SPDT = 1P2T, this is single pole, double throw.
DPDT = 2P2T, this is double pole, double throw.
Here's a helpful picture of the difference:
For the purposes of a power switch, I believe both of them would be alright, although I'd wait for another person to give confirmation as well (just in case).
Thanks crispy tofu. that confirms my initial thoughts. now just for confirmation on which i should use. like you say i dont think it would make a difference. From my understanding we'd only need to wire up 2 poles anyway....