Not to flog the dead horse, but I thought I would post my own results. With the SPTD driver in place, my average speed burning DVDs using ImgBrn in XP SP3 (32-bit) was 5.6x. When I removed the SPTD driver, I was pretty surprised to see that my burner (Pioneer DVD-RW DVR-112D) jumped to an average burn speed of 11.2x.
When you uninstall Daemon Tools, it does not uninstall the SPTD driver. However, you can download the latest Duplex Secure SPTD driver, run the installer, and it will ask you what you want to do. Simply click uninstall, reboot, and you are done.
http://www.duplexsecure.com/en/downloads
Thanks,
DD.