Well, an HD is pretty much nothig in terms of power consumption. I think it is save to say (and I have read it often) that it uses around 10W

I think a dualcore (AMD) with a very efficent PSU might be the better choice... It does not take a lot more power than a single core and still less than an Intel.

Take the smallest graphics card (or better none) you can find and leave the HD in... makes less trouble. And don't forget that Flash memory is supposed to have only very limited write cycles..

Thor