I was recently given 3 dual opteron 2400 servers with 4GB of RAM and 120GB hard drives. I am interested in setting up something similar to Amazon's EC2 for my own personal web development use. Basically, I would like to spin up instances from an ISO or other disk images and have them available to test and develop software.

Are there open source solutions I can use to accomplish this? I am assuming one of the machines will need to act as a controller of some sort for the other two.

I use Sun's VirtualBox on my local development machine to virtualize various versions of Microsoft Windows. However, I'm not sure if that's the best tool for what I am trying to achieve.

I apologize in advance if this question is to vague to get meaningful responses. I am new to cloud computing and fairly new at server administration.