ati mobility radeon hd 4650

hey guys,

my system (dell studio 1747):

CPU Type : QuadCore Intel Core i7 720QM, 1.6 GHZ
Motherboard Chipset : Intel Ibex Peak-M PM55
Video Adapter : ATI Mobility Radeon HD 4650
Physical Memory : 4096 MB (2 x 2048 DDR3-SDRAM ), 1.333GHZ
Network Card : Dell Wireless 1397 WLAN Mini-Card

i have succesfully installed the snow leopard 10.6.5 (first 10.6.3, then updated to 10.6.5) on my dell studio 1747 but i stuck at the point of getting my graphic card to work. it is the ati mobility radeon hd 4650. i read lots of posts and threads discussing this but none of them helped me...
is there any possibility to get it work and change the native resolution?
by the way: audio and LAN is no problem...

thanks for your help

Moved to correct forum, Laptops.