+1, Wine is typically a last ditch effort if you HAVE to have something that has no comparable application on Linux. As mentioned,
OpenOffice is incredible and absolutely free. There's your office suite.
For a media player, there are tons. You can look at
Songbird which is modeled to be an iTunes alternative, however I've found it not to be polished enough quite yet. Granted, I haven't used it in a while. Another very popular choice is
Amarok if you're using KDE (I suggest Gnome, it's the Ubuntu default, Kubuntu is the KDE version), or my favorite when I was last using Ubuntu,
Exaile on Gnome.
There are plenty of apps to replace just about anything you use right now. I'd suggest getting into the Ubuntu forums as they have a ridiculous wealth of information. You can find out about all kinds of cool new apps by just browsing around the forums.