Below are some of the best programs to have on your Windows desktop or laptop.
I have tested them and now use each one and they have proven to be invaluable to me.

Browsers - Firefox

Mozilla Firefox is the best Web browser out there. It is the ost secure and it has a lot of add-ons that enrich your browsing experience.

Anti-Virus - ESET NOD32

ESET NOD32 Antivirus is the most effective protection you can find to combat today's huge volumes of Internet and email threats. It provides comprehensive antivirus and antispyware protection without affecting your computer's performance. Social Media Scanner protects your Facebook® and Twitter® accounts against malicious content.

Anti-Malware - Malwarebytes

Malwarebytes' is an important security program for any computer user to have installed on their computer. It is light-weight, fast, and best of all, excellent at removing the latest infections that may be in the wild. Malwarebytes is updated numerous times throughout the day, which allows you to stay protected from threats as they come out. It monitors every process and stops malicious processes before they even start.

Utility - Revo Uninstaller Pro

The fastest, most secure and convenient way to remove unneeded applications and system components. Great, powerful and reliable alternative to standard Windows removal program.

File Manager - SpeedCommander

Packed with useful functionality, Speed Commander has many useful features that will help you manage your files. It is much more useful than Windows Explorer.

PDF Reader - Foxit Reader

Foxit Reader is a small, lightning fast, and feature rich PDF viewer which allows you to create (free PDF creation), open, view, sign, and print any PDF file. Foxit Reader is built upon the industry’s fastest and most accurate (high fidelity) PDF rendering engine, providing users with the best PDF viewing and printing experience.