You can have anything you want in Firefox, or Thunderbird mail.
I, hardly ever, use the Calendar, which does not come with either Mozilla or Netscape7.2. I, just, installed Calendar in the preview of Moz1.7.6 and FF1.02
. You have to pick the right version, although I don't know if it matters.
I access Calendar from the Preferences, for Mozilla, and Tools in Firefox. In Firefox, there is an additional goodie. You can get a Calendar icon on the Menu Bar, from View|Toolbars|Customize
But, don't expect anything in NS8 beta. Everything is up in the air.
I addition Mozilla has a standalone calendar, Sunbird.
I am considering NS8, and no more than that, and I am keeping up with Mozilla Suite, but I fail to see what all the noise about separate applications. Many websites are already supporting Firefox, while they were not supporting the Suite.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6) Gecko/20050319