You will not get much compression from most picture files as they
are already compressed. You should get compression from
raw tiff files but those files are enormous by comparison. You will get
get maximum compression from text, especially text with lots of spaces.
The compression will look for portions that are repeated and assign a
number and count to the repetitions and remove them, along with
compressing bits. This is why zip file can be different sizes depending
on the program producing them but still be read by the othe zip/unzip
programs. So if space is the primary concern you could use a program
that takes all night to produce a file about 1/4 the size of a regular zip
file something more of interest to software distribution.
Word of warning with a compressed file the loss of 1 character will
probably destroy the entire zip file. The loss of 20 bytes in a plain
text file might go unnoticed and not be as important where it occurs
As far as what was to be the main part of my reply, I see on rereading
that it is for company use and not personal use. In a company you
probably have server backups in place so perhaps don't have to worry
about your own backups. UltimateZip would be cheaper than WinZip
but if this is at a company you may have WinZip and you may have a
later operating system with a zip program in the operating system.
For those at home there are free programs which are better, in fact two
programs for the price of one that I like can be found
Backup to CD by zipping personal folders (#backupto_CD)
http://www.mvps.org/dmcritchie/excel/backup.htm#backupto_CD
the actual programs are
Back4Win - Backup Program by Alistair George Manufacturing
http://www.back4win.com/ (free for home use)
Creates zip files by your selection from a directory, great for
backing up to a CD with compressed zip files. I create one
zip file per main directory.
While Back4Win can expand them back and restore the file
I prefer using UltimateZip for that part. While you could zip
directories and store them on CD with UltimateZip, I prefer the
sensible GUI interface of Back4Win for doing that.
UltimateZip is free for home use (and for work is cheaper than WinZip)
http://www.ultimatezip.com/download.htm
handles more compressed formats than WinZip and has great context
right-click menus.