Linux - Desktop

Is it possible to have a total 'open source' IT system? One of the requirements for this would be a Linux-compatible desktop, where the proprietary software is replaced by open source equivalents.

The Linux desktop:

"as DESKTOP OPERATING SYSTEM, replace MS Windows with Linspire Lindows, Gnome, or BeOS Max' as INSTANT MESSAGING SERVICE, replace AOL AIM with Jabber; as OFFICE SUITE, replace MS Office with OpenOffice or Gnome Office ; as ACCOUNTING PROGRAM, replace Inuit with Compiere; for PROJECT MANAGEMENT, replace IBM Lotus Notes, with Horde Project, or Net Office Project; as DATABASE PROGRAM, replace MS Access with Twiki, Druid, Gnome DB ; for FAX MGT., replace Esher VSI Fax, with HylaFax or Mgetty+Sendfax; for BROWSING, replace Internet Explorer with Firefox." (personal communication, inspired by a Wired article)

Mono is an open source alternative to the Microsoft .Net specifications, at http://www.mono-project.com/about/index.html

Five fundamental reasons why Open Source projects do not make great inroads amongst ordinary users, at http://www.firstmonday.org/issues/issue9_4/levesque/index.html#l5

And this blog entry with discussion gives additional reasons why “Linux is not ready for the desktop’, see http://weblogs.mozillazine.org/asa/archives/008499.html