Although furtive eavesdropping on computer activity is certainly possible, the specific tale presented above is nothing more than an example of "government conspiracy" type hoaxlore. It originally appeared on
www.chromance.de (from which it has since been removed, although it remains mirrored elsewhere), a site which carried several other obvious hoaxes. The graphics for the article were lifted from another site's page about commercial keyboard loggers, and the purported letter from the Department of Homeland Security appears to be an altered version of someone else's example of correspondence from the DHS.