Mozilla FireFox is an excellent alternative to Microsoft Internet Explorer, It is one of the most popular open source web browsing software developed for windows. This web browsing software is much more secure and safer from viruses, worms, spyware than the MS Internet explorer. It has feature like Smart location bar for easy and quick access to URLs and offers simple convenient operation and configuration as per user taste.
VLC player is an open source media player from VideoLan project team for windows. It is an excellent media player which can play different format of multimedia files such as MPEG -1, MPEG -2, MPEG -4 Quicktime, AVI, DIVX, OGG, and many more in addition to windows format media files. It also supports streaming protocols and can be used as steaming server for unicast or multicast mode of streaming. The library of codecs used for encoding and streaming is outstanding. It has inbuilt synchronization option for audio and video when played together.
Media Player Classic is another free open source media player application for windows which can play multimedia file of almost in all format.
Open Office is a full fledge office suite and is becoming popular very fast. It has all features that is spread sheet, word processor, data base, power point presentation, etc. which are available with the Microsoft Office suite. The files created in Open Office are compatible with Microsoft Office and vice versa. It is a very good and free available replacement of Microsoft Office suite. Open Office also support many other open formats too.
Clamwin is a free but very effective anti-virus, anti-spyware program for windows. It has provision to schedule scanning; automatic updates download and add in to Microsoft Outlook for automatic removing virus-infected attachments.
Bit torrent client is very popular open source software which allows easy down load of multiple files through internet. It is an excellent program which takes cares of connectivity interruptions very efficiently.
Media Coder is windows based open source software allows ripping of CD and DVD for video. The video so ripped can be converted into variety of formats for playing and using with different media player. Handbrake is also a good DVD to MPEG-4 DVD ripping tool.
Apache Web Server: Web has rapidly becoming a powerful tool for dissemination of information and providing platform for contacting and generating business. Apache web server, developed as an open source alternative on windows platform can be used as replacement of IIS (Internet Information Services) web server utility of Windows 2003 server program.
NVU is a simple and effective web page creation software which makes web page designing and we be site maintenance very easy without much knowledge and technical expertise of HTML.
Open VPN is windows based open source program used for establishing a secure communication over the internet using SSL security feature. It offers good configurations range such as remote access, site-to-site VPNs, Wi-Fi security etc. The program is implemented over OSI layer 2 or 3 using SSL/TLS protocol for secure networking and supports certificate, smart card based client authentication process. It is a good cost-effective alternative in comparison with other VPN technologies for small and medium enterprises.