Starting asterisk

hello sir

Actually when i install AsteriskNow iso file it first wash(clean) the hard disk and then install.
in which mode (graphical / text ) i install it that i not loss my previously install software. i have install (asterisk-, libpri-1.4.7,zaptel-,subversion,and all library related it ) my problem is Asterisk iso file
is it necessary to install

Shiv kumar
9953956681 … 510480.pdf