In Windows Explorer, browse ro c:\your download path\E3SP2ENG\Setup\ folder and Run the file update.exe by double clicking it. The installation wizard should appear. Click Next, Click the radio button next to I AGREE and to accept the SP2 License Agreement, ant then click Next.
The Pre-selected installation options will appear, such as:
Update - Microsoft Exchange - Current Ver. 6.5
Update - Microsoft Exchange Messaging and Collaboration Services - Current Ver. 6.5
Update - Microsoft Exchange System Management Tools - Current Ver. 6.5
Installation Path c:\Program Files\Exchsrvr
The Installation Summary will appear, which is a recapitulation of the above options that were pre-selected and not changed. Click Next.
The installation Component Progress will appear and a check mark will appear in front of each of the following when they are installed:
Micorosft Exchange
Microsoft Exchange Forest Prep
Micorosft Exchange Domain Prep
Microsoft Exchange Messaging and Collaboration Services
Microsoft Exchange System Management Tools
Completed the Microsoft Exchange Wizard
Recommend Restarting Windows Server to save the new settings after applying Exchange 2003 SP2. Also recommend backing-up the installation or entire O/S. It may be easier to use something like Bart's X-PE to boot your server, and use Ghost 9 to backup an image (or images of each) installation and data partition, saving those partition images into a pre-named folder on an attached external USB drive. You can restore from there if you later have a problem with configurations after installing Exchange 2003 SP2. This is only recommended before configuring exchange mail boxes or before using ExMerge to restore mailbox data from a retiring Exchange Server.