You can't open vba on it's own, it requires a host application, in this case word.

To keep Word from showing, comment out the line Word.Visible = True.

If you're going to do that, I'd turn on error handling (On Error Resume Next) to ensure the Word application closes, although that depends on how well your Word macro handles errors too.

You could also trap errors and report them using the Err object. There's a reasonable vbscript write up on error trapping here:

http://www.juicystudio.com/tutorial/....asp#errhandle