problem opening word or excel files

Recently I installed Windows XP on my computer.
After that I installed Office XP but I choose to keep previous Office 97.
All worked fine.

After that I went, in a folder, on tools -> folder options -> files types and then I choose to add a new options for opening excel and word files by default with word or excel 97 but with possibility to choose either word or excel XP with a right click on the file.

After those changes when I double click an excel file with a name who have more than one word
Example: “My excel file.xls” the program first try to open my.xls, excel.xls, file.xls and at last he open “My excel file.xls”

How can I change that?

Thanks