I know this thread has the potential to start a flame-war, but I was recently wondering what would it be like if I were to transform my digital lifestyle to open source and free (as in Willy) software?
So here is the list of software that I use:
Operating System
Ubuntu
www.ubuntu.com
Splitting Videos
Avidemux
fixounet.free.fr/avidemux
Image Editing
Gimp
www.gimp.org
Video Player
VLC
www.videolan.org/vlc
Acrobat Reader
Adobe Reader
www.adobe.com/products/reader/
PDF Editor
PDFEdit
pdfedit.petricek.net/en/index.html
Bittorrent Client
Transmission
www.transmissionbt.com
Edonkey
aMule
www.amule.org
Office Suite
OpenOffice
www.openoffice.org
Vector Art
Inkscape
www.inkscape.org
Chatting
Eampathy
live.gnome.org/Empathy
Encryption
TrueCrypt
www.truecrypt.org
IDE
Eclipse+PyDev
pydev.org
Compression
Q7Z
code.google.com/p/k7z
Disk Catalog
Gnome Catalog
www.gnomecatalog.org
DiskSearch
disksearch.sourceforge.net
Alarm
KAlarm
www.astrojar.org.uk/kalarm
FTP
FileZilla
filezilla-project.org
Mind Map
Visual Understanding Environment (VUE)
vue.tufts.edu
Download Accelerator
Flashcard
Password Manager
KeePassX
www.keepassx.org
Equation Editor
Mathtype, OpenOffice
Personal Accounting
HomeBank
homebank.free.fr
Backup
Back In Time
backintime.le-web.org
Music Player
Amarok, Rhythmbox
Antivirus
ClamAV, ClamTk
www.clamav.net
clamtk.sourceforge.net
Project Management
Planner
live.gnome.org/Planner
Books/Movie Catalog
Tellico
tellico-project.org
Calibre
calibre-ebook.com/
Screen Recording
GTK-recordmydesktop
recordmydesktop.sourceforge.net/about.php
Virtualization
VirtualBox
www.virtualbox.org
File Synchronization
Unison
www.cis.upenn.edu/~bcpierce/unison
Disk Burning
Brasero
projects.gnome.org/brasero
Audio Editor
Jokosher
www.jokosher.org
Internet TV
Miro, Boxee
www.getmiro.com
Desktop Publishing
Scribus
www.scribus.net
CHM Viewer
CHMSee
code.google.com/p/chmsee
Note Recorder
Xournal
xournal.sourceforge.net
Text-To-Speech
Text Aloud in Wine
Information Management
Remus
remus-software.org
Notes
ZIM
zim-wiki.org
Idea Generator
piggydb
piggydb.net
Desktop Effects
CompizConfig
Recipe Manager
Gourmet Recipe Manager
grecipe-manager.sourceforge.net
DJVU+PDF
Evince
projects.gnome.org/evince/
Firewall
Firestarter
www.fs-security.com/
Webcam
Cheese
live.gnome.org/Cheese
Productivity
Gnome Do
do.davebsd.com/
Batch Video Converter
HandBrake
handbrake.fr/
I still keep looking for good free apps and I must admit I enjoy the overall Apple experience, but it's too expensive in my opinion.
guild 
