Jerry,

Simply open your catalog settings, and you'll see the path and the filename of your currently open catalog:

This is the file you want to back up manually.

The folder you were refering to ("C:\ Users|Jerry\My Pictures\Lightroom\ Lightroom 4 Catalog-2 Previews.lrdata") is a folder containing your previews, which is normally not worth being backed up (they can be recreated using your catalog and your originals, and they tend to be very large).

Backing up the backup folder of the LR catalogs also makes sense, as this is a versioned backup of your catalog, not just the latest state (which could be corrupt at the time of backup).

Beat

Jerry,

It is normal that the catalog file itself (the database) is a lot smaller than the previews folder. The catalog file almost only contains text (it also ZIPs very well, btw), while the previews folder contains images (your previews), which take up a lot more space. In my case, the catalog file itself is 400MB, while my previews folder is 32GB. The size of the previews folder also depends on size and quality of previews rendered.

Recreation of the previews is done from the Library module:

Library -> Previews -> Render Standard Size Previews (or 1:1 Previews, whichever you desire)

This can take quite some time, depending on the number of images in your catalog, but can be run unattended while doing something else.

If you get "Preparing to install", the link between the *.lrcat extension and Lightroom seems to be broken. Try changing the default program associated with *.lrcat by pointing to "C:\Program Files\Adobe\Adobe Photoshop Lightroom 4.0\Lightroom.exe" using the procedure described here:

http://www.sevenforums.com/tutorials/12196-open-change-default-program .html

This should make Lightroom your default application to open *.lrcat files.

Beat