How to save power on computers?

Have you switched to green computing? Well, even I am not sure how to move to green computing, but one thing I can say about this, that is we can use a computer that requires less power. Hence may be a laptop is a greener PC. And yes I have started using laptop long back, it is been 1 year now,but this post is not about green computing. This post is about how we can save power with our computer. I work in IT industry. In our building there are thousands of professionals working. Last we got an mail that as it was going to a long weekend, so our admin requested us to turn off the computers before we leave.

Well, just think how much power do we waste by not turning off our pc everyday, I understand,if it is needed we can leave our PC on, but at least everyone of us can switch off the monitor, even that will save a lot of power.Or companies can train the house keeping stuffs, so that they can switch of the monitors, and the lights when people leave from a bay. This can help to save bill and hence improve profitibility too.