I would avoid using select * (as indicated) because of the potential of design changes.
If your select * from table ever does a filter by a parameter - you may want an index.
For example, select * from table where id = 12
But per your question, if it is limited to select * from table, kill the index. The advantage of not having an index is that you can write (insert) records generally much quicker into the table.
-jb