Microsoft Excel initiating at the wrong OS

Hello all.

I have installed Windows 7 on my Mac OS X.

Everytime I click on some excel files in Windows, the excel or Numbers in Mac will initiate instead. I want to use it in Windows, not OS X.

How can I stop this from happening?

Thank you.

 

This is a serious issue. I did not faced this issue before. Some one may help you.

Thanks