The HK has the correct analog inputs, the Onkyo doesn't.
On the Creative sound card you will need to use the analog LF/RF, Center/Sub and LR/RR analog outputs.
Hard to say on the power consumption, it goes up and down depending how much energy is needed to run the speakers.
PS: As receivers go, he HK is pretty nice. Doing some more reading on it, it has decent amps in it. Most receivers will rate 50 watts per channel but is usually just for the 2.0 and then they have trouble providing the power to the other channels.
The other thing is that HK includes the analog inputs which most receivers(only higher end ones include those or surround processors) Also, the HK has a serial port input so that you can connect your PC to do firmware updates(updates the software in the receiver).