> I am new to all of this...very new. I want to
> back-up my blogger blog and was linked to this
> download.  I am not clear with what HTTrack is and
> what site mirroring does. 

A mirror is a static copy of one or more pages from an internet site including
related images, etc.  Static means all server side processing, like searching
and dynamic content, don't exist.  Only plain html and associated files.

> 1.Does it store the huge
> amount of info from the blog on my hard drive? 

The amount stored depends on the site and the mirror options.

> 2.If I delete my cache, is the mirror going to be
> gone? Where is the "mirrored" blog going to be
> stored? 

The mirror is stored on your hard drive where ever you want it to be. It has
nothing to do with your browser's cache.

> 3.I don't think I want it on my hard drive...I would
> think it's too big and will slow computer
> performance/internet speed. HELP?
The mirror is on the hard drive, it doesn't require a network.  You look at
the pages with any browser.

If you want to backup your blog, use the back-end tools available for your
site.  Dump the database etc. 

httrack is a front-end tool, like any browser's save-as command.