So, to answer the question about RAR files:

RAR is the native format of WinRAR archiver. Like other archives, RAR files are data containers, they store one or several files in the compressed form. After you download an RAR file from Internet, you need to unpack its contents in order to use it.

from http://www.rarlab.com/rar_file.htm

I use WinZIP to open RAR and other compressed files.

-Joe-