"Start small.: Rome was not built in a day, so you can't
suddenly shift all your software lock, stock, and barrel to open
source. Check out the low hanging fruits in open source software,
like OpenOffice.org, the open source office suite, Mozilla
Thunderbird the email client, and so on at the desktop. Trying them
out doesn't cost much other than your personal time. Then, move on
to more complex open source products.
"Start with Windows based Open Source Software: A direct follow
on from step 1, open source doesn't mean Linux. There're plenty of
open source software available on Windows as well, so try and get
your hands onto those. Linux can be intimidating initially for a
lot of people, so start using Open Source software on Windows, an
OS that everyone's already comfortable using."