You should run setup from an Administrator account to set file types
associations; each time you want to change file types associated with
PeaZip or to reset PeaZip's configuration you can just run this setup
again.

Unistalling older version of the software before installing the new 
one is recommended, but not mandatory.

You can select multiple files and/or dirs and use "SendTo" menu to 
send them to PeaZip's most used function (i.e archive, add to zip, 
extract here, test, encrypt etc), otherwise you can doubleclick on 
associated filetypes to open supported archive types.
You can also create similar entries, pointing to PeaZip's most used
functions, in Context menu.

You can save input layout of archives to speed up future operations,
save job definitions to be used in scripts and get detailed job log 
after each operation.

PeaZip too can be used from scripts and command line, refer to program's
documentation for details.

Transparence effect requires at least Windows 2000 (otherwise the
program will not use transparence); Windows XP or Vista recommended 
to offer best GUI aspect.