cyclegadget:
Here is the mosfet that I used with the 3x3x3 and I think it big enough for my 5x5x5. It is a ZVP2106A
The OP's schematic indicates that he needs to switch 1.28A, which implies that in order to keep the voltage drop and power dissipation low, the Rds(on) needs to be low. I suggest a maximum Rds(on) of 0.1 ohm, and that is what I looked for when I searched for suitable mosfets. The part you linked to is designed for 10V gate drive and even then it has Rds(on) of 5 ohms. So it isn't really suitable for this application.
I suggest either the mosfet that Crossroads selected, or the SMD part I linked to along with some SOT23 to DIP adapters such as these http://www.ebay.co.uk/itm/10pcs-SOT23-Dip6-Adapter-PCB-SOT-23-6-/360441877952?pt=LH_DefaultDomain_0&hash=item53ec0295c0.