实现搜索如谷歌搜索文本框

I need to implement the search (to show students name) similar like google suggests textbox. I am using .NEt 3.5 . From client side i am planning to use updatepanel(Ajax search) and from backend using Linq to SQL. Once i fetch the data I am planning to store into cache to avoid multiple db calls based on the keyword. So if user type 'Joh' then cache will contain all the student name starts with 'Joh'. So if user types 'John' then from cache I will be able to filer it. I need to implement the search (to show student