How to find whether Sql Server 2005 x86 is installed or x64 is installed?

Say you have multiple instances of SQL Server and on mixed platforms such as 32 bit and X64 bit platforms, so how do you find which version of SQL you have installed. If you are well versed with the environment then by looking at the servernames you can mention so. But how about a new DBA started and need to perform a set of actions on X64 editions and with no documentation available! SELECT @@VERSION or SELECT SERVERPROPERTY('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition')...(<a href="http://sqlserver-qa.net/blogs/tools/archive/2007/07/29/how-to-find-whether-sql-server-2005-x86-is-installed-or-x64-is-installed.aspx">read more</a>)<img src="http://sqlserver-qa.net/aggbug.aspx?PostID=1181" width="1" height="1">