yeah, what he said =)

8 ohm current will run about 0.64A, and 4 ohm will run 1.29A, and run 3.32W, and 6.63W (3.32W per resistor If you run two 8Ω in parallel) respectively. The heat sink should be real nice, hopefully it didn't set you back too much though.

looks good to me, you've just got to connect the grey power ok to a red 5v line and the green one to a black line.

for more info see here (from red's site)
http://www.marcee.org/Articles/PCPowerSupply.htm