Display value from dropdown to textbox

Iam having one dropdown and two textboxs(dates)

based on the selection from dropdown i have to disply the dates......

dropdown tb1 tb2

dropdown consists of all,this week to date,this month to date,this year to date

if u select 1.all:whole 2years should be displayed in textboxs

means in tb1:jan1 2007 tb2: dec 31 2008

2.this week to date:this week starting in tb1 ie nov 4,2007 tb2:nov 6 2007
3.this month to date:this month starting in tb1 ie nov 1,2007 tb2:nov 6 2007
4.this year to date:year starting tb1:jan 1 ,2007 and in tb2:nov 6 2007

getting nothing , please tell some in proper way

Your question is quiet confusing . Please post your question clearly.