Do a CRTL-SHIFT-ESC which should bring up Task Manager. Check both the Applications tab and Processes tab. Make sure you have a small number of items under Applications. If you have any antivirus software running, disable it as well.
If this doesn't help, count the number of items you have in the Processes list and in your system tray. We need to disable as many as we can. If you're not sure what each icon or entry is, then post back.
To be honest, you shouldn't have to disable too much for it to work right in XP. Try visiting Creative Labs website and browse the support section...some DVD drives prefer to leave DMA disabled.