Comment Re:Newer, just to reduce the power bill (Score 3, Informative) 272
P4 desktop I picked up for nothing a while back - hence not a huge power suck
Hate to burst your buble, but the P4 is about the worst CPU power-wise you can get, if it happens to be a northwood it isnt THAT bad, but prescott based P4s are frickin space-heaters. You should put a kill-a-watt meter on the thing and calculate its power-cost, chances are that replacing the P4+mobo with an Atom-based mini-itx might work out in a year or so.
As for the carbon footprint thing, if you are just replacing drives for the power-usage (rather then needing more space), i do not believe you could ever compensate for the CO2 produced in the production/shipping of the new drive. (not within its operational lifetime anyway)