Back up the files to another disk change the os and restore the files.
There are Windows Server, Linux, BSD, and even Apple's own server
The difficulties of using a Linux or Unix server are no different than an other server OS - they have the same challenges and difficulties.
They are all operating system.
The difficulties are the same regardless of any modern server operating system; I don't believe there are any that are that specific to Unix or Linux that might not be shared with other operating systems.
The Subsystem for UNIX-based Applications (SUA)For a UNIX or Linux client, SUA creates a multiuser environment complete with commands, case-sensitive abilities, programming tools, shells (runtime environments), and scripts. With SUA installed, even UNIX/Linux programs can be ported over to Windows Server 2008.
In general Linux has no restrictions on the number of users in a server. Commercial Unix vendors vary in what they allow by licensing, so it depends on the vendor.
No, but Linux is based on Unix since Linux is a Unix clone.
Rather than listing them all here (which is subject to change), it would be better if you went to the web sites for the various flavors of Unix/Linux to check on what processors are supported.
Linux hosting and Unix hosting are not exactly the same thing. Linux hosting and Unix hosting refer to the software operating system employed by the servers of the host. The primary communication being made when a server is described as Unix or Linux is that it is not a Microsoft product. Unix comes in several proprietary versions, Sun Microsystems (now Oracle) and AT&T are two well known commercial versions of Unix. They own and control intellectual property associated with Unix. Linux is a nonproprietary version of Unix. There are many flavors of this. All are "open source." The intellectual property is controlled by one of the various open source models, GPL being the most well know. If a person says they have a Unix server, they may or may not mean the proprietary version of Unix. For many people, unix is a generic reference and can mean Unix or Linux. If a person says they have a Linux server, then it is a Linux operating system. It may be one of over a hundred different types of Linux, but it is based on an open source version of Unix. Note that it is possible to co-mingle the proprietary and nonproprietary versions of Unix, but this is not typically a matter of concern unless you are an expert or unless you are using Apple's version of "open source" Linux. Apple's version works pretty much like open source Linux, mostly, sometimes.
The Odd OneLINUX, UNIX, SOLARIS are the UNIX based operating system.SQL SERVER is a database system from IBM.
For this purpose you need a server OS, for instance, windows server 2000, windows server 2003, windows server 2008 and so on or Linux based systems as well as Unix. For windows it's very simple just add role for your server to be a domain controller and follow instructions. For Linux based systems as well as Unix you can find information in Google there is a lot of it.
Linux is an open system, Unix is not.