How can I find whether the SQL Server 2005 installed is a 64bit or 32bit?

Sometimes a situation arise when few features of SQL Server don't work on 64 bit version and a developer is not aware of which version he is using. In order to know about SQL Server version, you can use

SELECT @@version

This SQL statement will tell you the following information
- SQL Server Version
- Edition
- Processor family - 32 bit or 64 bit

Example is:

Microsoft SQL Server 2005 - 9.00.1399.06 (Intel X86) Oct 14 2005 00:33:37 Copyright (c) 1988-2005 Microsoft Corporation Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 1)