how to Upgrade/migrate MS SQL 2005 SP3 X86 to X64 with 40+ live databases

I have 40+ live databases on this server below is the info on MSSQL 2005.

Microsoft SQL Server Management Studio            9.00.4035.00            SP3      Standard Edition
Microsoft Analysis Services Client Tools            2005.090.4035.00
Microsoft Data Access Components (MDAC)      2000.086.3959.00 (srv03_sp2_rtm.070216-1710)
Microsoft MSXML                              2.6 3.0 6.0
Microsoft Internet Explorer                        6.0.3790.3959
Microsoft .NET Framework                        2.0.50727.3603
Operating System                              5.2.3790       Windows server 2003 Standard Edition x64 SP2
                                          
Hardware environnent                         HP DL380 G5 2 x 2.83Ghz Quadecore, 8GB RAM

I have some future plan of installing high end Enterprise Project Management solutions which requires x64 bit architecture of MSSQL too… I would like to get my existing MSSQL server which is X86 get converted to X64 what steps are involve; please provide as much info as possible.