There has been lot of debate about how linux and open source softwares that whether it saves cost or it is just a manipulative perception but from my perception it does with various points it scores really well as compared to other OS, softwares and also reduction in privacy.
Linux desktops operating systems such as Fedora, Ubuntu, OpenSuse, Debian etc are free and quite stable with excellent hardware support. Server based operating systems like Centos,Ubuntu Server are giving stiff competition to Redhat Enterprise Linux and Suse Linux Enterprise Linux. Even this OS can be installed without license leading to no updates and no technical support that makes them more acceptable.
OpenOffice, Kingsoft office, Libreoffice are best alternatives to Microsoft Office and their installables on Windows OS have been also in great demand.There are various video and audio players in linux like Cmus,mp3blaster,mplayer,vlc which also serves your entertainment purpose.
If you talk about webservers nginx,apache are more scalable and preferrable choice of web servers than other windows based webservers like IIS.
Open source load balancers like haproxy,pound, balance which are also quite comparable and competitive in terms of commercial load balancers based on cloud like elastic, cisco or F5 Big IP.
All browsers firefox,chrome,few others are available on Linux.Even for kiosks based applications the OS choice is Linux.Android where you can root your own device and upgrade your own mobile operating system isn’t that so exciting and wonderful as compare to other mobile OS.In Linux you have the choices of virtual 3D desktops and cool wallpapers.Car Infotainment and in flight entertainment systems runs linux.
All compilers like gcc,g++, python,perl,cgi etc are also available in Linux. LAMP(Linux apache mysql php) can also be configured. Postgresql, Maria DB, MongoDB can also be installed and configured in Linux environment. AutoCAD alternatives like FreeCAD,QCAD community edition fulfill your needs of designing. Even for UI designing you have all the alternatives you need for Adobe Illustrator etc which you can find on http://www.linuxalt.com/.
You have skype, pidgin and all the IM’s for Linux as well.Even for Visio you have Dia and yed software for diagrams and designing architecture workflows.
In short there is nothing you cannot find an alternative in Linux. I leave it on you to decide that Linux really helps in cost reduction and providing more stable environments in terms of server and desktop needs.
Please free to comment and queries.