Can somebody send me the required VS51.exe for visual studio- keil integration

I guess you're referring to this:

http://www.keil.com/forum/docs/thread9966.asp

Unfortunately, the author didn't leave any contact details!

:-(

And he didn't respond to a similar recent request:

http://www.keil.com/forum/docs/thread15864.asp

So you may be out of luck, I'm afraid.

Thanks for the info Andy,

So do u know in what other way i could achieve the objective? i.e. building the project in MS visual studio with keilC51 tool chain?

You're just going to have to study the VS documentation that describes how to integrate external tools - and do that!