Registry cleaning software like CCleaner, RegCleanXP claim to delete the junk of your Windows Registry databases. But does that make your computer work any faster ?

One of the MVP recently wrote that Registry Cleaners are useless, as Windows XP *never* reads the whole registry, but only the necessary keys when needed. Each and every unnecessary key will just be ignored.

Another one said that some registry entries might be obsolete but are still accessed by some program and could effect the performance of that program (which could be part of the system). 

Most of the members are of the view that regular disk defragmentation is better than a registry cleaner – not the one that ship with XP but a third-party disk defragment like Acronis Disk Director, Raxco Perfect Disk or Disk Keeper.

What your take on that ?