How to use more than 4GB RAM on SQL Server?

This article describes the procedure to make sure your SQL Server is able to use more than 4GB of RAM, if installed

How SQL Server Index Statistics works - Part 2

This article demonstrates the real world examples of how SQL Server utilizes the index statistics.

How SQL Server Index Statistics works - Part 1

This article describes the concept of index statistics in SQL Server and how it is used in query optimization.

Selectivity of a Query and how it affects indexing

If you want to understand how selectivity of Query works then read this article.

Cache Efficient Dynamic SQL Queries and how Query Plan Caching works in SQL Server

This article describes how sql server query plan caching works. It gives you working examples of how to write cache efficient dynamic sql queries.