Office XP and Vista help!!!!

I use Vista Home Premium edition and Office XP.

The problem is I am unable to set the .DOC files to be opened by WINWORD.EXE.
Even if I tried using the default access manager I am unable to select the WINWORD.EXE, even after I browse for and select it…

please help me out…as it is very annoying that whenever I try to open .doc file, it is showing the “open with” dialog…