Erm let's get one thing right people. ELECTRICITY KILLS, get you facts straight. A little knowledge is a dangerous thing...read on...
For DC systems it is the combination of current AND voltage that kills people. You could quite safely touch a 5V or 12V power rail (or phone line) and not get a shock because the resistance of your body inline with the nearest conductor will most likely render the potential difference insubstantial. NOTE, it is doubtful you could ever get electrocuted by a phone line (it is probably impossible). The moment you short-circuit a phone line power rail you get a voltage drop to almost 0V and the current dies respectively, therefore it is insufficient to cause any damage. Hence why no-one tries to cheat the phone companies by running their house off the 'free' electricity in the phone line. There just isn't enough power there!
In AC systems (the UK uses 240V at 50Hz and 13A) it is proven to be the combination of voltage, frequency and current that kills. Unfortuanetly it also so happens that the combination of UK electricity specifications are one of the most dangerous in the world. Brilliant!
In conclsuion: Be careful guys and girls. Ensure your PC is earthed securely!