difference between UPDLOCK and FOR UPDATE
FOR UPDATE is not valid SQL Server syntax in a regular SQL statment, it is used when you create a cursor.

But you are probably using ADO with CursorLocation adUseServer and then your query actually works because ADO will use sp_cursoropen which accepts the syntax used for cursors.

The default behavior in SQL Server is that cursors can be updated so specifying for update does nothing for you unless you also specify a column list.

Specifying the updlock query hint on a cursor will only do things for you if you are running in a transaction. With updlock the locks is placed when you do fetch next from ... and without updlock the lock is placed when you do update ... where current of, still only if you are in a transaction.  

So in your case, using updlock will place locks when you fetch data if you are in a transaction. If you don't use updlock, in a transaction, you will place the locks when you update the data. If no transaction is present there is no difference between the two and you could as well not use any of them.