computer to install it. And the NSA probably doesn't have the time or money to install such devices on individual computers. VPRO can probably make it a lot easier for them!
Devices such as keyloggers, for example, can be concealed completely inside an innocuous-looking connector:
Similar things to turn on/off older computers would be trivial to make, using a radio-frequency signal, or the X10 home automation protocol, or similar ways.
Software solutions probably exist, but they would likely depend on M$ WinBlows. Heck, I wouldn't be surprised if they are BUILT-IN to M$ 'Blows, which I wouldn't touch with a ten-foot pole.