Plone (http://plone.org) is a CMS that you can use to setup a portal or intranet with features similar as Google Docs. In fact, there's a module that let you write math using latex format: http://plone.org/products/latex-math-image

Plone is not only open source, but has a strong support from its community as any successful FLOSS project and also professional provided by a network of business and people in more than 60 countries as you can check in http://plone.net/

it should be vim vs emac here