Blender 2.6x Luxrender install help appreciated

[kalpana]

Hi there.
I've been messing about for a couple of days trying to get Luxrender to work with Blender & failing miserably.
For some reason when I follow instructions that I've found out there on the interweb pretty much nothing changes.
I've been trying to install the plug in from the User Prefs "Install Add On" function.
I expect I'm missing something screamingly obvious.

Is anyone able to give me a step by step on how to get this up & running?

Rig spec:
Ubuntu 12.04
HD7870 GPU
i52500k CPU
8Gb RAM

Even POVRay or Yafaray would be helpful I think.

Any help is greatly appreciated.