One of the "improvements" in VB 4.2.0 was the Activity Stream. However it is debatable whether it should really have been made the "default" page. For example on Qapla.com going to Qapla.com Forum by BOP5 will bring you to the Forum Index. That is my personal choice because I think VB sites usually are first and foremost, forums.
However since VB4 Suite was launched the CMS Homepage (content.php) had bee the default page so many people got used to it.
While 4.2.0 changed the default to the Activity Stream it also introduced a very easy way to change the default to any "tab" you want. Articles (the CMS), Forum, Blogs, or any other tab you may have setup in Navigation Manager.
Check out the long image below for easy to follow step-by-step directions:
