A Computer icon on your desktop gives you easy access to all mounted drives and your home folder at one place just like Windows does. Here is how you can show the Computer,home,network and Trash icon on your Ubuntu Desktop.
Press Alt + F2 and type gconf-editor in the dialog box and Click Run to start the GNOME Configuration Editor.
Now you need to Go to the apps/nautilus/desktop from left menu and On the right hand side,you need to check the following options
You can do few more things from that place too, change the trash_icon_name,home_icon_name,network_icon_name and computer_icon_name.
That's it now you should see The Computer, home and Trash,Network icons on Your Ubuntu desktop