I have just found another site with some useful speed tweaks all displayed on one page for quick access.
It is the most useful page for tweaks I have come across.
It includes the tweak you posted about turning off indexing service.

http://www.pccallouts.co.uk/freetutorials.html

It covers 18 Windows XP Speed Tweaks.

They include:

1. Remove/Replace Windows Background image
2. Edit Boot.ini to disable GUI boot
3. Disk Cleanup
4. Disk Defragmenter
5. Visual Performance
6. Windows Explorer Performance
7. Applications Autorunning on Startup
8. Cleaning the Windows Registry
9. Remove viruses, trojans and spyware
10. Apply Windows updates
11. Disable performance counters
12. Optimize your internet connection
13. Remove windows fonts
14. Disabling indexing service
15. Turning off system restore
16. Speed up boot sequence
17. Disable unnecessary services
18. Setting manual IP addresses