Composite and GLX

[420djoe]

Hi!
I have Xfce-4.2.0, Xorg-6.8.0, nvidia-kernel-1.0.6629 and 
nvidia-glx-1.0.6629 running on an AMD k6-II.
I enabled composite in xorg, but I get a message saying that composite 
and glx can't be used together.

Is there a way to have glx and composite?
Is there any other application or feature that can provide transparency?

Thanks.
Miguel

ps: sorry for any spelling mistakes, I'm not English