I used the image from download.astaro.de and burned it with 24x on a QSI DVD+-RW SDW-0825 without any problems.
The CD booted without any problems on a Pentium M, 1.5GHz.
The same CD didn't boot on a DVD-ROM LTD122 (Athlon XP2800), but i used a working 5.000 CD, booted up the system and switched then the disks for installation...and it worked.
(The ISO booted within VMWare on the same machine.)