[Christ]

Easiest way to build a green PC - Low power monitor, and conservative on the specs. Your daily use PC doesn't need to be a gaming machine with 500GB of HDD space. IF it does, you need to delete some of your pr0n.

OS tuneups are necessary, so get ready to work with software if you're not familiar already. Yes, Windows DOES become completely stupid after about 3 months of regular use. It happens, get over it and learn to fix it.

Keep programs that you use frequently loaded in memory on startup, lose everything else. This will allow you more room in memory before your computer needs to start using Pagefile (Virtual memory) to save things. virtual memory is a cell on your HDD that means your computer will wildly spin up your HDD randomly for a single data bit of memory that it takes ~400ms to find.

Don't use an 800w PSU if you don't need it. Overdoing it here can actually cost you a bit, as the capacitors and resistors and other components are more plentiful in a larger capacity PSU. They turn electricity into heat, moreso, the more of them there are.

These are just a few tips to help.

I actually use a 90W PSU in my old system, and I run 2 80GB IDE HDD's with a 700mHZ Athlon (card-style CPU, socket A) and 768mB ram. It runs XP, with a few tweaks to make it do it's job better, and more efficiently. It's actually faster than my old Vista retail PC at most daily functions.

Of course, you can save power by upgrading your internet connection too... the faster you browse, the less time you need to spend in front of your computer.