UltraVNC (64-bit version)
My family has a dangerous habit of blindly clicking through software installs and downloading all kinds of junk from the Internet. Luckily for them, I can repair the damage anytime from my home or office using the free UltraVNC remote control software.
You can install and use UltraVNC in several different ways; in my experience, it's easiest for the person I'm helping if I run the remote viewer on my machine, and then send a simple applet to them via an e-mail attachment that they click to automate the link to my system.
To set up UltraVNC on your PC, install the application and select Run UltraVNC Viewer (Listen Mode) on the program's Start menu. If you have a router, you may have to open a port (the UltraVNC's default is 5500) to redirect traffic to your local computer. The method for doing this varies from router to router, so check your device's documentation or the vendor Web site.
Note: This program is donationware. It is free to try, but the author accepts and encourages donations towards further development. This software comes in 32-bit and 64-bit versions. This is the 64-bit version, which is for 64-bit PCs running a 64-bit OS. If your PC is running a different supported OS, please download the 32-bit version instead.
--Jon L. Jacobi