Which version of linux is the newest and is usually used for a server?
Which version is best used as xp and vistas equal?
Is there a website that I can still go to to downoad these free?
What book would be the best for learning these operating systems(linux)?

Thank you!

Which version of linux is the newest and is usually used for a server?
That depends on the distribution of Linux you choose. There are many different distributions each with its own latest release. Some of the distributions of Linux (e.g. RedHat) have different versions depending on whether you want a workstation or a server. Other distributions have one version that can be used on a server or a workstation which is chosen at the time of installation.


Which version is best used as xp and vistas equal?
I'm not sure I follow your question but maybe if you take a look here Linux Online - Distributions and FTP Sites (http://www.linux.org/dist/) you might find your answer.


Is there a website that I can still go to to downoad these free?

Yes. The above link is one of many sites that point at various distributions.


What book would be the best for learning these operating systems(linux)?

The same site above has some suggestions for books.