Here is the list of top 10 best free programs for your PC. All are free to download and use.

Open Office
A free alternative to Microsoft Office suite. Open Office contains applications for word processing, spreadsheets, presentations, graphics, databases and other purposes.
www.openoffice.org

Gimp
If you don’t want to cash out a lot of many for Adobe Photoshop license, then Gimp is the right software for you. Gimp may be a bit less user friendly then Photoshop, but with large set of functionalities it’s a great free alternative to Photoshop.
www.gimp.org

Avast Antivirus
Good and capable free antivirus software. Automatic updates of virus definitions, realtime file scanning and scheduled scans are just some of the features that Avast offers.
www.avast.com

VLC Player
Even though there is a pretty large selection of free media players out there, VLC Player stands out with it’s support for just about all video formats that you may come accross, as well as support for network streaming of video files.
www.videolan.org

Firefox web browser
This currently most popular web browser in the world, Firefox offers user friendly interface and fast and secure Web experience. New version of Firefox had over 8 million downloads just in first 24 hours and currently holds Guiness World Record for the most software downloaded in 24 hours.
www.firefox.com

Thunderbird email client
Mozilla Thunderbird is free and feature rich email client, which is in many ways better than Microsofts Outlook application. Great support for multiple accounts/inboxes and great spam filter are just some of the highlights of this application.
http://www.mozilla.com/thunderbird/

Adobe Reader
Adobe Reader enables reading of PDF files and is an absolute must have for every computer user. The best of all is that it is completely free.
http://www.adobe.com/products/reader/

WinRar
More than often we need to “pack” files in order to free up some disk space or send the files over Internet. WinRar is one of the most powerfull tools for this purpose. Besides it’s native RAR compression format it also supports ZIP and many other formats.
www.rarlabs.com

MSN Messenger
One of the most widespread instant messaging programs on the Internet. Nowadays better known by the name of “Live Messenger” this tool enables users to send instant messages (chat) with one another or with groups of people. Besides text messages, phone calls, pc to pc calls and video conferencing is also supported. In order to use the program you need to have a Hotmail email account set up.
messenger.msn.com

Spybot S&D
According to leading online PC magazines, Spybot S&D is the best privacy software available. This tool searches hard disk for tracking cookies and spy- and ad-bots, responsible for sending your private information (like surfing habits) accross the Internet to ad-serving and similar companies, and removes them if found.
www.safer-networking.org