UnPlug n' Pray

To protect the system against external intrusions from hackers of malicious programs like trojans, worms and other such malware requires a proactive attitude from all users, especially if the system runs antiquated versions of Windows.
The older they are, the more prone to exploits they become and operating systems prior to and including Windows XP are more vulnerable to attacks. At some point, quite a few years back, a critical flaw that could have allowed the takeover of virtually any workstation was discovered.
This weakness resided in the UPnP or Universal Plug n' Play services that were set to default as active with every installation of the OS. To correct that issue, apart from the solutions offered by Microsoft, independent developers made some dedicated tools to rectify the problem.
Among those, UnPlug n' Pray is one of the most easy to use and it focuses on a single task, so there is no way someone could get sidetracked when using it. As soon as yo run it, the application will display in its main window the current status of UPnP and in case it is enabled, by pressing one button the user can deactivate it.
This networking capability, otherwise useful, but utterly dangerous on older operating systems, especially if they do not have the patch installed, can be re-enabled. However, its advisable that you do so only after making sure that the potential security holes are sealed.
Very easy to use and highly effective insofar as the purpose it was build for is concerned, UnPlug n' Pray is definitely the tool one would need to quickly solve one of the most important security concerns that affects Windows XP and older OSes. Even if it only sports a single button in its main window, the program does it job very well.