LXDE is a very lightweight desktop (My install runs on about 300 MB RAM). This desktop environment is ideal for the user that who wants to install a secure operating system on an old computer. This environment is very intuitive for anyone who used a Windows system in the last decade. The only downside is the appearance of the desktop; to run on minimal resources the shell does not have any bells and whistles, so the computer looks like an old operating system.
In addition to using this environment for old computers, this is also my environment of choice for creating a separate ‘computer’ to use for online banking and shopping.