first download the Android Froyo iso or you can visit the download page and select an iso or img file yourself. Now you can use this CD image in two ways.
1. with VirtualBox
2. as a bootable USB
first i will explain how to use it with VirtualBox.
if you don't have VirtualBox installed download and install it. then run it and create a new instance.
likewise clicking next will create a new instance.
then double click on Android-x86 and start the instance.
and then click on the place where i have circled
next thing add the downloaded ISO and attach it
right. after finishing it you can use Android !!
select Live CD or if you want to install it to your virtual hard disk select installation.
if you experience that you can't use your mouse inside Android(use mouse and there are keyboard instructions as well like escape for going on step back) go to Machine and Disable Mouse Integration. or press Host(normally the right control key + I) once your mouse is captured press right control to come back to host operating system
it is up to you to explore Android with VirtualBox
as i told earlier the second way is to make a bootable USB with this ISO to do it first download UnetBootin and run it.
Select Diskimage and browse and open the iso file then check whether you have an USB in the given drive and click ok it will take sometime and create a bootable USB. so you can boot your computer with that USB and use Android as a Live CD or install it to hard disk....
Cheers !!
Kesh