I am using Windows Vista and I had a preinstalled MS office home and student 2007 version as it was a trial version I reinstalled the same and then installed MS office 2003 which i am quite familiar with.

Now when ever I am opening a word document I get a windows installer asking me to install ms office home and student version 2007 and its disturbing me too much.

How can I stop this windows installer asking for automatic installation

Word files might be associated with Office 2007, check the file type in Windows Explorer. Tools > Folder Options > File Types, locate DOC file, click on the button Advanced, check if those operations such as Open, Edit, etc., make sure they are associated with Office 2003.

Just my guess.

Oh I tried it even then when ever I open the documents I get the installer asking me to install MS office Home and Student 2007.

Bad luck

What is happening is the conventional, OFFICIAL uninstall does NOT really do this--Uninstall, because it leaves stuff in your Windows Registry

What you have to do is use something like use the FREE Revo Uninstaller and then when asked do you want a complete Uninstall you do, and then click to uninstall ALL the registries so M$ no longer sees any sign a program is or WAS on your machine--Revo's Wizard will walk through the process

Now reinstall what you want

I have already uninstalled MS Home and Students 2007 so when I use Revo I am not able to find any of the 2007 files but when I open a ms document i keep on getting the windows installer asking me to instal ms off 2007

Can you reinstall the offending programs, then use Revo

What is happening is your Registry is still "remembering" stuff

You have to get this stuff out of there and Revo is the easiest way I have found to clean out Registries of left over junk