If you do not have the Desktop tab under Display Properties (right click on
free space on your Desktop and pick properties) propably the value of the
ClassicShell entry is not 0.To check this out navigate along :

- HKEY_CURRENT_USER\Software\Microsoft\Windows
\CurrentVersion\Policies\Explorer\

Locate here in the right pane the entry :

ClassicShell

If the entry is not there,you need to create it.Just create it if you experience
this kind of proplem.(right click in right pane , new , REG_DWORD , name it
as mentioned above)

Doubleclick the ClassicShell entry set it's value to 0.(disable)

Note:
The missing Desktop tab is a well discussed issue on forums.This tweak
seems to not always solve this propblem.(I did not test it,as i do not had
this problem yet,but i investigated opinions and results to this.I have read
from people where it worked well,by some people it brought back the tab but
the options/features in the tab did not work.
Microsoft states the same method for this issue.