Technically, both changes (or neither of them) generate the same 
output binaries, so I Don't Care(tm). My approach for disabling the 
warnings in the code has (to me) two advantages:
1. You immediately see that warnings are disabled. I would otherwise 
never expect that to happen in any serious project, because warnings 
are valuable.
2. You only have to do it once for the single source file, not in 
every VC project file.

Happy weekend!