Saving datetime in sql server and retreive rows sorted by datetime??

Question

Hi
I need to have a row in my table (sql server 2008 express) and it needs to be possible to make calls to sql server like "all the products with datetime older than xxxx-xx-xx-xx.xx.xx.xxxx". How should I save the data in my table so i can use it for sorting when retreiving data? As a sql timestamp or a string? I have heard some negative talk about the sql timestamp and have not heard of nayone using it. At work we save timestamps as a string but that i db2 we are using.
Any suggestions??