There are two ways to stop applications from auto-starting when you login to Windows Vista. You can either use the System Configuration Utility or the new Software Explorer in Windows Defender:

The first option is to use the System Configuration Utility

1. Click on the Start Button, enter msconfig and hit Enter.
2. Click on the Startup tab.
3. Uncheck items that you do not want to auto-start and click OK.

The second option is to use the new Windows Defender

1. Click on the Start Button, enter Windows Defender and hit Enter.
2. Click on Tools from the top menu bar.
3. Click on Software Explorer and select Show for All Users.
4. Select an application to either Remove or Disable

These options will help you to optimize your Vista experience and give you more control over your computing environment.