EDIT: This thread is a merger between two different threads made on the same day. -DarkED
One commonly asked question is "Does Linux have an alternative application to Windows application X?" This is for the Ubuntu/Kubuntu/Xubuntu system, but almost all can be used on most Linux distros. This is by far not a complete list, and there are larger ones on the internet which I can post / gather links for as well. If you know of more please don't hesitate to add them!
Windows || Linux
----------------
MS Office || OpenOffice / KOffice
WinZip || Ark
WinRar || Ark
Adobe Photoshop || The GIMP / Krita
Windows Media Player (Video) || Kaffiene / mplayer / VLC Media Player / gxine
Windows Media Player (Music) || Amarok / Rhythmbox / Juk
Nero CD/DVD Burning Software || K3B / Gnomeburn / cdrecord
3D Studio Max || Blender
Internet Explorer || Firefox / Konqueror / Opera
IM Client / Trillian || Kopete / Gaim / Pidgin
BitTorrent / uTorrent || BitTorrent / Ktorrent
Notepad / Text Editor || Kate / Gedit / VIM / nano
Address Book / PIM || Kontact / KPIM
Control Panel || SystemSettings (KDE) / Administration Panel (GNOME)
Partition Magic || QtParted (KDE) / GParted (GNOME) / Parted
Winamp || XMMS / Beep Media Player (Thanks Electrohacker, I kinda forgot about these)
Limewire / Kazaa || Frostware / GTK-Gnutella
CuteFTP / SmartFTP / WS_FTP || KFTPGrabber
Microsoft Frontpage / Adobe Dreamweaver || Nvu / KompoZer (Thanks Pirate-M.Lifnen)
Windows to Linux Conversion:
In Windows --------- In Ubuntu
Internet Explorer --------- Firefox
Microsoft Office --------- OpenOffice.org
Winamp -------- Xmms
Photoshop --------- Gimp
AIM, ICQ, MSN, Yahoo!, Jabber, IRC instant messaging --------- Gaim
Word Pad (or notepad) --------- Gedit
Windows Media Player --------- Totem
iTunes --------- -for playing music:
-----------------------------Rhythmbox
----------------------for iPod Syncing
--------------------------------Gtkpod
ID3 tag editor ----------------------- easytag
MIRC -------- Xchat / Konversation
Premiere (Movie Editing) --------- kino
Bittorado --------- Bittorado
(don't you love
native ports)
Dreamweaver --------- Nvu
CDex ---------- Sound Juicer
Nero -------- Gnomebaker
Outlook Express --------- Evolution, Thunderbird
Snood ---------- Frozen-bubble
Partition Magic --------- Gparted
eMule ----------- aMule
Soulseek ------------- Nicotine
DC++ -------------- Valknut
any multitorrent client ------------ Azureus
any download manager --------------- D4X or Gwget
regedit -------------------- gconf
Adobe Illustrator ------------ Inkscape
Remote Desktop Connection ------------ Terminal Server Client
Windows Explorer ------------- Nautilus
Windows Picture and Fax Viewer ------------ Image Viewer (Eye of GNOME)
Paint ------------- Jdraw
This link has a much larger, and more complete list for those who didn't find what they were looking for.
The table of equivalents / replacements / analogs of Windows software in Linux. (Official site of the table)
Those are just a few examples of alternative software you can use. There are many more examples, too many to list. Linux has at least one alternative application for every Windows application.