Sql Query for retrieving the Records which are 3 months old

Question

Hi Experts

I have a problem with writing a sql query

I have a table in my database which holds the datetime stamp by name DateCreated(Column Name)
I have other column in my table which is Id.
I wanted to retrieve the Id Records which the DateCreated is not null and DateCreated should be less than three months

Here is the format of my Date 6/24/2011 10:56:03 AM
Any suggestions
Please Help