OK,
to launch the planeshift setup application, simply do the following:
Click start, then all programs, then select planeshift, and then click on planeshift setup.
That should launch the setup program and you should be able to see something like that:

(taken from another forum thread, you\'ll see it without the red circle

)
There you can tweak some things, for instance, ensure that sound (bottom left corner) is turned off (click on the round button next to \"off\") also check that \"vertex buffering\" is also \"off\" and ensure that neither load all maps or keep maps loaded have a check on the circle next to them (so they\'re both disabled to save RAM)
More things to try, at the bottom right, you\'ll see \"texture downsampling\" move the bar to the right (you can check different values and adjust as you find it fits you the most) I just saw that \"multisample for quality\" thing that perhaps can be unsticked to free more resources.
That from the planeshift setup utility.
More things to check, programs running on the background, ensure you don\'t have a cpu consuming application running, such an antivirus or an hdd defragmentation utility that is scheduled to start when you\'re playing the game, for instance.
As for the fullbright, how to apply it.
Click on Start, then all programs, then planeshift, then go and _right click_ on planeshift - tech demo. A prompt menu will appear, there, select Properties.
You\'ll have automatically highlighted a line that says (blabla...)psclient.exe\"
put your cursor at the end of it, hit the space key and type -fullbright
So the text should look like (blabla...)psclient.exe\" -fullbright
(notice the blank space between \" and -)
Simply accept the changes and launch the game normally, let\'s see if you can play now.