How to reinstall Windows Defender on Vista ?

On my desktop I have defender installer package, when i try to reinstall, it won't let me reinstall the defender.

There is an error message (the attached file).

Windows Defender

Installation Error

The wizard was interrupted before Widows Defender could be completely installed..

Your system has not been modified. To complete installation at another time, please run setup again.

Click Finish to exit the wizard.

Finish

How do I install my Windows vista without using XP on the Hard drive?

Or is that even possible?

Guys,

I am using Windows Vista in my system. The taskbar hides automatically every time when I run a browser in full screen mode. But when there is no browser opened or not in full screen mode the taskbar does not hide. Can you please help me to solve this?

How does disc cleanup work in Windows Vista?

I tried it once and it showed almost 10GB of data to be cleaned. But after completing disc cleanup my drive show only 4GB of the data cleaned.

Dear friends

Iam using Windows Vista, has a wide range of fonts but still i need more fonts to be added.

A command for adding more fonts is not available in the font folder for a glance.

Thanks

Which is better, Windows Vista or the Windows 7 and what make it better from the other? Please give some ideas. Thanks! 

How will I replace my old OS (Windows Vista) with Windows 7 since my previous OS could not be installed?

Hello friends,

What are the facilities of enabling Windows GodMode?

How can we enable it in Windows 7?

I use windows vista which was preinstalled in my laptop.

In which I had to drive parted. One (10 GB) was for windows recovery and another one (222 GB)  for anything else.

How to make partitions of hard disk when you have only one drive left to do anything?

Hi friends, when I am running my laptop working on internet. I am getting an error message "Your computer is running on low memory. Please close some program".  How can I fix the problem?