If you want to move the firefox cache to another location use this link click here
Basically you create (if it's not there) the file user.js in your profile folder, then add the following lines to it which specifies where the cache will be located. Mine looks like this,
// Path to Cache folder:
user_pref("browser.cache.disk.parent_directory","F:\\Temporary Internet Files");
so my cache lives on my F partition inside the tempory internet files folder (so everything is in one place).
Hope that helps, Rob.