MiKTeX 2.7 MiKTeX 2.9 ?

Up to now I am running MiKTeX 2.7 (and am quite happy with it).
Now I read in the official MiKTeX manual that it is possible to 
install various versions of MiKTeX (2.7 and 2.9, in particular)
side by side; so - not only for reasons of curiosity - I also
installed MiKTeX 2.9 -- in a completely separate folder.
The installation succeeded without problems.

But how do I know which version am I now using,
and how  do I choosebetween the two ??

Any help is appreciated.

ccn.
-- 
..................................................................

   Prof.Dr. Cornelius C. Noack
   Inst. f. Theor. Physik FB 1
   Universit"at Bremen               Phone    : +49 (421) 218-62031
   Otto-Hahn-Allee                   Fax      :              -4869
   D - 28334  Bremen                 home     : +49 (421)  34 22 36
                                                     Fax:  346 7872
   E-mail: noack at itp.uni-bremen.de   or   ccnoack at mailaps.org
   WWW-page: www.itp.uni-bremen.de/~noack
..................................................................

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