How to prevent these executables from starting up?

Permanent solution (this will work even when an application is updated or reinstalled):

1. Press Start and type Local Security Policy, and press Enter.
2. In the left pane, click on Software Restriction Policies.
3. Then, in the right pane, double-click Additional Rules.
4. Right-click on any empty space in the right pane and select New Path Rule....

5. Click browse and select the program you need to block. For example, DivXUpdate.exe could be in C:\Program Files\DivX.
6. Make sure the drop-down list under Security level says Disallowed.
7. Click OK and you're good to go.

I'd suggest not doing this for GoogleUpdate.exe, as it could interfere with Chrome's auto-update. Instead, just remove GoogleUpdate.exe from your system startup (use msconfig or google how to work the registry to remove startup items). Also, run Task Scheduler and disable the Google Update task.

• GoogleUpdate.exe
  This is a scheduled task. You can remove it or disable it from there. Find the Scheduled Tasks item in the control panel.
• iPodService.exe/iTunesHelper.exe:
  These are services. Go to the start menu, choose run, and then type services.msc to view the services management snap-in. If you have an iPod or iPhone, you might find you actually want to leave one or both of these running.

• Reader_sl.exe
  This is started via the \\HKEY_LocalMachine\Softare\Microsoft\Windows\Current Version\Run key in the registry. Adobe will restore this key every time it updates, so rather than removing it entirely you might want to just break the entry (change it to point to a non-existent location), and then (as administrator) change the permissions on that entry such that no one has access to update it (but this might also prevent Adobe from updating correctly in the future)

  You might find a few other entries here you don't need as well, but be careful, as it's easy to end up removing something from this list that it turns out you were using after all.

I'm unfamiliar with the other items in your list.

For my part, I have a bat script that I run now and then that removes these, as well as a few other annoyances (the Acrobat desktop shortcut and Start Menu item, the Microsoft Silverlight start menu item, and the Apple Quicktime shortcuts and start menu items).

Not much for several of them I know. Many software apps, including iTunes, Adobe Reader and Chrome, are designed to check for these processes and replace/re-enable them whenever they can't find them or they see they aren't running. Sometimes you can have temporary success in suppressing them, such as replacing iTunesHelper with an empty executable file that does nothing. But the apps just keep replacing them.

About the only option I have heard of for a permanent solution is one guy I read in a forum created his own service that continually watches for these other processes and kills them when it finds them running. Harsh, but he said it worked. But that was a couple years ago and I don't recall where I saw it at.