Hardware acceleration is not always setup for you on Linux. Often you need to install some drivers. Here are some links to various locations where you can get drivers for various cards.

For most cards you need DRI (Direct Rendering Infrastructure) found here. If you have nVidia you must install the nVidia drivers instead. They can be found here.

On Debian GNU you can install nVidia drivers with 'apt-get install nvidia-kernel-src nvidia-glx-src'

If you don't know what kind of card you have try one of the following:

X :1 -scanpci
cat /proc/pci
or see "Device" section of /etc/X11/XF86Config-4

If you have other information about setting this stuff up email me so I can put it up here :)