Cache size and Mozilla v1.7.5

Since I am on dial-up once in a while, I try to surf many Web sites to 
download images to cache. I set Mozilla v1.7.5's cache to 150 MB in 
Windows XP Professional SP2 (all updates). For some reason, it never 
goes over 100 MB. Sometimes, the size goes down to 50 MB.

How can I have Mozilla cache a lot of stuff to hold so dial-up wouldn't 
be so painful when I have images load enabled? I understand it will 
delete old cache data, but a lot of the data are reused over and over 
since I visit the sites almost daily.

Thank you in advance.
-- 
"The men of experiment are like the ant; they only collect and use. But 
the bee...gathers its materials from the flowers of the garden and of 
the field, but transforms and digests it by a power of its own." 
--Leonardo da Vinci
    /\___/\
   / /\ /\ \      Phillip (Ant) @ http://antfarm.ma.cx & http://aqfl.net
  | |o   o| |      E-mail (nuke ANT if replying privately to a newsgroup
     \ _ /           post): [email protected] or [email protected]
      ( )
Ant is currently not listening to any songs on his home computer.