Mind if I have a say on applications?

Whatever I'm going to say it.

Best AntiVirus with real time protection
NOD32

Internet Browser(s)
Opera Internet Browser - full of features out of the box and fast. (works on just about everything)
Safari + Webkit - FAST (Works on Windows, but really made for Mac)
Firefox - Decently fast cleans up after itself memory wise, and has good extension. (Works on Windows 2000 or higher, Linux, and Mac)

Best Audio Players:
Amarok ( made for linux KDE )
Banshee ( linux GTK )
aTunes ( Linux more effects than iTunes but stablity is currently lacking )
iTunes ( windows does have afew others though, but meh.)
WinAmp

Best Video Players:
Something that plays video's no best here i tend to like Totem since it supports some neat plugins.
VLC Player is good.
K Lite Codec pack is useful for most video players since it is a giant codec installer.

Instant Messeging:
Mac (Aduim)
Linux ( GTK Pidgin, KDE Kopete )
Windows ( Trillian , Pidgin )
Of course nothing beats the native IM messenger for something, but running 5 messengers can be troublesome.

Office:
OpenOffice.org - Held down by trying to get compatibility for non standard formats (hacking a format takes lots of time.)
MS Office - Sort of...


I know of a load more applications, but i don't feel like it.

Ok this is IMO best apps out there.

Best AntiVirus with real time protection
AVG Free
Avast Home
AOL McAfee Internet Security
Ad-Aware

Internet Browser(s)
Konqueror (Linux)
Seamonkey (Windows, Linux, OS X)
Safari (OS X and Windows)
Firefox (all)

Best Audio Players:
Amarok (Linux)
aTunes (Linux)
Windows Media Player 11 (Windows... duh)
WinAmp
MusicMatch Jukebox v7 (outdated but back in the day, IT was the best)

Best Video Players:
VLC Player (Linux, Windows, OS X)
Media Player Classic (Windows)

Instant Messeging:
Gaim/Pidgin (I'm pretty sure it's for every OS)
Trillian (Windows)

Office:
StarOffice, What OpenOffice was based on. It's been around since 1999 and is way more stable then Open.
Microsoft Office, I Don't care If you think M$ SUCKS!!11 It's the best Office App Ever!

Movie Editor:
Adobe Premier (Windows, OS X)
Microsoft Movie Maker
iMovie (OS X)
Kino (Linux)

Audio Editor:
Audacity (all)
Acid (Windows) <--- Best Looper ever!