linux equivalent for most common os x apps

[Netzer Antonio]

i'm running 2.3, haven't done the upgrade to 3.0 yet
i'm using the kde gui.

i was wondering what your favorites apps, or the ones that most closely 
resemble these other apps

music player:iTunes  ......
instant messenger: Fire (allows me to connect to several accounts 
within one app)
browser: I use camino and safari
is there a caller id app for linux???
these are the apps the people using the computer use mostly.....

i'll try to upgrade my 2.3 to 3.0 over the weekend, maybe there are 
better programs with it.


also, is there a good web page, to find linux software?
i've tried download.com

thanks

Netz