Songbird
Over 50 Languages
Windows: Windows 7, Vista, XP SP3 Mac: Mac Intel OS X 10.5+
"Download the Songbird player and rock your mobile. Take your music with you, share playlists with friends, watch video, find out when favorite bands play your town, and discover new tracks by hot new artists."
http://getsongbird.com/
http://getsongbird.com/system-requirements.php

Songbird is huge, and has quite a few memory leaks. It uses a lot of RAM.

I don't even use it as an installed program, and would never even try to portabilize it.

The non-portable one I always fall back to is Winamp. Portable: AIMP.

This is just my opinion, of course.

Try MusicBee

You can run it as portable too

Preferences -> General -> Run as portable application

but at the moment it's just available in english

This is the excellent player and opensource.

Can we add to Liberkey http://www.getsongbird.com/