Windows 7 - Server running Windows vs Linux

So I do not know much about servers but I heard that almost 50% of servers are running Linux these days cause they are more secure and cost effective. Is all this true, can someone please educate me. thanks.

there is many kinds of servers, web, storage, database etc.
it all depends on what services you want to provide.
and as for security there is no such thing as 100% secure and for cost is not only OS licence and hardware, but support maintenence etc.

Lots of people run servers on Linux. Without a doubt, the primary reason is to avoid licensing costs.

Imagine if you will, that you work for a small company and you want to put up an FTP server for your customers to use to download files and so forth. So, you can go out and purchase a copy of Windows Server 2008 R2 for around $700. This is for 1 server license and 1 CAL (client access license).
Microsoft Windows Server 2008 R2 Standard - license - P73-04982 - Windows Network Software - CDW.com

If you intend to run a public FTP server with anonymous access...no additional licenses would be required. If you intend to have usernames/password for users and you intend to use IIS, you would need either CAL's (client access licenses) for these accounts or if you were going to have to purchase the Internet Connector license if you intend to give logons to any customer who needs one. A 5 user CAL pack is about $175. (Microsoft Windows Server 2008 - license - R18-02503 - Windows Network Software - CDW.com). The unlimited option is around $1999 (if memory serves). If you use a 3rd party commercial FTP app that manages usernames/passwords...CAL's are not required, but the purchase of the FTP server would be.

Now, if you contrast that to a Linux server, you can install CentOS Enterprise Linux 6 for free. Then you can install something like vsftpd, for free. Create all of your user accounts for free, and you total out of pocket license fees will be 0. Of course, this requires that you know something about Linux and can configure and make it work. For somebody with a little Linux experience, you can setup a new FTP server in about 30 minutes. I can do it in less than 10 minutes...and that includes loading the OS.

So, there are tons of servers on the Internet that are running Linux. And it's mostly due to licensing costs. Why pay money to Microsoft to host these types of systems when it can be done for free;
--Web Servers: Apache is the most popular and often runs on Linux
--DNS servers (BIND): across the Internet, BIND is the most used DNS server for ISP's and big corporations.
--Mail servers: Many mail systems run sendmail or postfix as bulk sending systems.

As far as security, Linux is built pretty secure...but can always be setup badly and compromise security. However, I do feel that Windows Server, by it's very nature is often setup and administered by people who don't have much in terms of qualifications. Because it looks like XP, Vista, 7, many can simply click around and can manage to get it setup and working without too much effort. Many will often disable firewalls and turn of security features in an attempt to figure out why it's not working and then simply leave it that way. Contrasted to a Linux admin, Linux can be arcane and many servers don't include a GUI of any kind. Thus, you have to have some knowledge of what you are doing to even get it working. If the average person walks up to a Linux command line and the cursor is just blinking they are going to be lost and get nowhere. If on the other hand, they walk up to a Windows server GUI and start clicking around...they may in fact manage to install an FTP server and get it working. But that doesn't mean that what they did is remotely secure.

I did not realize Windows was so expensive in there server edition. I am sure it is easier to use but damn learning the command line has to be less pain full then the damage on your wallet.

I am no pro at the command line but google made it somewhat easy when I used Fedora.

I love the command line....while you can load GUI's to your Linux servers, I never do.

Command line makes setup and documentation a breeze. I can just write down a bunch of commands and somebody who doesn't know anything about Linux can simply cut and paste them and it's all setup. Lots easier than screen shots showing what to click, what to choose, which radio buttons and check marks to hit, etc.

Since everything is file based, it's so easy to backup. Let's say you have that FTP server above. You can copy the /etc/passwd file (got your user accounts), the /etc/shadow file (got your user passwords), the /etc/vsftpd.conf file (got your ftp server configuration) and /etc/iptables (and you got your firewall configuration). Now, if you have to build a whole new Linux servers, you can replace these 4 files and you are pretty much right back in business.