Use the OrElse operator.
If myDataSet2 IsNot Nothing OrElse myDataSet2.Tables("CurData").Rows.Count > 0
EDIT: See my comment on your original question. You are PROBABLY looking for:
If myDataSet2 IsNot Nothing AndAlso myDataSet2.Tables("CurData").Rows.Count > 0
That will check if myDataSet2 isn't null. Assuming that it's not, it will then check that there is at least one row. If it is null, then the second condition won't be checked.