In the Ubuntu 9.04 unsupported ATI graphics card on the machine or even run Ubuntu Live is a problem, can not access the GNOME desktop, only to enter the character interface, only in the character interface to the ATI graphics card installed driver:
$sudo apt-get Install build-essential autoconf automake libtool pkg-config git-core
$sudo apt-get Install Libdrm-dev x11proto-gl-dev mesa-common-dev xutils-dev x11proto-xf86dri-dev X11proto-fonts-dev X11proto-randr-dev x11proto-video-dev X11proto-xext-dev X11proto-xinerama-dev x11proto-render-dev Xserver-xorg-dev
$git Clone Git://anongit.freedesktop.org/xorg/driver/xf86-video-ati
$CD Xf86-video-ati
$sudo./autogen.sh--prefix=/usr--enable-dri
$sudo make
$sudo make Install
The above command is open source version of the ATI driver, has been able to support the majority of the new ATI graphics card, you may wish to try.