Whenever you start or restart your Amazon Instance, it will change your time zone back to GMT (if you changed it). As I am going to install Microsoft SQL Integration Server and Microsoft SQL Reporting  Server, I want the time zone to be GMT+1.

To stop Amazon to changing the Time Zone:

• Open %programfiles%\Amazon\Ec2ConfigSetup\bundleconfig.xml
• Change the SetSysPrep from <Yes> to <No>

Amazon will also change your machine name, which is not usefull when hosting an SQL Server (think about the connection string). You can also change this behavior (also change the SetSysPrep option explained above in this article):