Of the mentioned VoIP packages with XMPP support, Jabbin is what I think best.
It gave the best hearing quality and worked on a range of different neworks and speeds without ruining the sound quality.
Its ability to send and receive files at such incredible speeds was also the best, with its only competitor being skype in this scenario, and it was much faster than skype.
Worked well on Ubuntu 12.1 however lagged a little on Windows 7
