Web Forms :: Parse To Label Date Dropdownlists?

I'm generating reports with a table, these reports are between some dates, the query is working, the thing is that the client does not want to have to type the date as for instance, reporte between 2010-10-01 and 2010-10-31. Since he only wants to get monthly reports, he wants to sleect just month and year. I created 2 dropdownlist one with month and another with year. I don't know if it is the best approach but what I want to do is that when the client seleces january 2010 automatically passes to 2 labels like this: 2010-01-01 and 2010-01-31 So then my query get these dates in the between fields.