Concatenate day month and year

 Hi All,
I have a field for the user to fill up his date of birth.
The field has three dropdownlist for selecting the day,month and year.
What I want is that once the user select his date of birth using the 3 dropdowlist and clicks on the submit button his date of birth gets stored in a single column of the database in the format  for ex .05/26/2010. I am using sql server 2005 and C#.
Please advise.
Aurum
 
...