Problems with Gigabyte GA-MA785GT-UD3H & ATI HD Radeon 4200

I install backtrack on my computer,the motherboard of which is GA-MA785GT-UD3H with ATI HD Radeon 4200 origionally installed. The problem is that backtrack can't find the vedio card.
When i type pyrit list_cores it shows

The following cores seem available...
#1: 'CPU-Core (SSE2)'
#2: 'CPU-Core (SSE2)'
#3: 'CPU-Core (SSE2)'

and when i install the driver downloaded from the official website,the driver say also that it cannot find the card.

So can anyone help me????

as far as i know to enable pyrit stream support u need to install ati-driver which is broken right now.

Firstly i install libgl1-mesa-swx11-i686,and reboot,then everything is OK.
But if i install ati-driver and reboot,I just can't 'startx' ------nothing appear but a black screen.
I'm wondering if backtrack has found that i have install the graphical card.