It's not necessary to build ati-driver for Ubuntu Hardy.
You need only build the kernel-modules.
Download the tar-archive: mach64 drm modules
and build the modules:

tar xzvf drm-mach64.tar.gz
cd drm/linux-core
make mach64.o
sudo cp *.ko /lib/modules/`uname -r`/kernel/drivers/char/drm/

... or install deb-pakages:
To install add the following line to /etc/apt/sources.lis:

deb http://debs.bakarasse.de hardy mach64

You will also need to add my key to your list of trusted keys:

apt-get update ; apt-get install bakarasse-keyring

next run again

apt-get update

Install for generic kernel:

apt-get install linux-ati-mach64-drm-modules-generic

...for Real time kernel:

apt-get install linux-ati-mach64-drm-modules-rt

...for 386 kernel:

apt-get install linux-ati-mach64-drm-modules-386

Dont forget, max Display Depth must be set to 16 bit (xorg.conf)

Here Hardy's xorg.conf sections with my changes:

...
Section "Device"
        Identifier      "Configured Video Device"
        Option          "ForcePCIMode"  "True"
EndSection
...
Section "Screen"
        Identifier      "Default Screen"
        Monitor         "Configured Monitor"
        Device          "Configured Video Device"
        DefaultDepth    16
        SubSection "Display"
            Depth       16
            Modes           "1024x768"
        EndSubSection
EndSection
...

After depmod -a restart the X-Server.

alex@max:~$ glxinfo | grep direct
do_wait: drmWaitVBlank returned -1,
 IRQs don't seem to be working correctly.
Try running with LIBGL_THROTTLE_REFRESH and LIBL_SYNC_REFRESH unset.
direct rendering: Yes
alex@max:~$ cat /var/log/Xorg.0.log | grep -A5 -B5 Direct
(II) ATI(0): [DRI] installation complete
(II) ATI(0): [drm] Added 128 16384 byte DMA buffers
(II) ATI(0): [drm] Mapped 128 DMA buffers at 0xb6757000
(EE) ATI(0): [drm] Couldn't find IRQ for bus id 1:0:0
(II) ATI(0): [drm] Falling back to irq-free operation
(II) ATI(0): Direct rendering enabled
(==) RandR enabled
(II) Initializing built-in extension MIT-SHM
(II) Initializing built-in extension XInputExtension
(II) Initializing built-in extension XTEST
(II) Initializing built-in extension XKEYBOARD

glxgears and openGL-screensavers work.
IRQ-Problem remains unsolved,
set it in BIOS on my laptop is not possible.