Hi Rai,
The icons on the lower right hand corner are programs which load in when your computer starts. These programs start when your computer starts to provide to instant access to them when needed. For example your Anti Virus program would be there if you have it so that it can detect virus on real time on your machine. Your MSN would be loaded there so that you can access it instantly. Real player would be loaded so that if you chose to access a real video, it can start up instantly instead of having to load the whole application.
Bottom line is - the more icons you can on the lower right corner of your task bar, the slower your computer will run since these applications are taking memory of your machine.
The way to disable them is the follows - depending on the applications.
1. They might be in the STARTUP folder. All the applications in the startup folder gets executed when your computer is started. To see what's in your startup folder do the following:
Right click on START - select EXPLORE. It should take you to the Start Menu. Now, expand the PROGRAMS folder and find the folder called Startup. In this STARTUP folder you will see some Application Files, which get run when your computer starts. You can delete these files if you don't want them to run during start up. The files in there are mostly 'shortcut' files so you can delete them without deleting the actual Program files.
2. In some applications, you need to open the application and view the options and find out which option defines the application being loaded in during startup.
Hope this answers some of your questions.
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Regarding the icons on the lower left of the screen - next to the START button, these icons are merely shortcuts to open your applications. Instead of having to click Start - Programs - and the application file to open the application you want such as Microsoft Word or any other Program, you can choose to put any Application shortcut on the Task Bar by simply click and dragging the application to the task bar to put a shortcut there that you can click to load the program.