Well, do you want basically unlimited space? Then set it to 1000 or 5000 mbs, then you'll never get full. Setting it to 0 or 1 will just delete the files right after they're loaded. For instance, say I go to google.com, and my files are set to store 1 mb of history. Now, since it's 0, right after I leave the page, it will be deleted, because it's only there for what I'm viewing, not being stored at all.
-SkyHi