Hi , I just did a quick test on EC2 instance with Windows 2003 . It was very easy , i used amazon supplied image i.e. AMI.
After right click on instance through Amazon management i can connect the terminal window as seen below.
Which password ? .. Hmm good question . Right click on windows instance in amazon mgt and click get password , it will show you encrypted password below that you see a textbox put the private key text which you downloaded earlier. and later it will show the password.