I found a post on how to get an ec2 instance to auto-login to a
desktop each time it boots or re-boots. Here's a summary of the
steps:
1. Download and install TweakUI tool and use it to enable
autologon(Logon->Autologon):
http://b.mrpl.co/wFhJec
2. In the Ec2ConfigService tool, turn off "Set the computer name..."
3. Turn off "Set a random password..."
4. Turn off "Enable SetPassword feature..."
This is useful for those times that Windows installs automatic updates
and reboots your instance.
One caveat: Once you set it up this way, you'll have to log into your
ec2 using the /console or /admin switch on your RDP client to make
sure you always connect to the already running console session.
DJ