How to move a Windows instance to a different EC2 data centre?

have you tried this very recent feature: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-copy-snapshot.html?ref_=pe_2170_27415460

I think it does just what you need. I tried to upload an image, but my reputation isn't high enough yet.

According to http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/Using_LaunchingInstaceFromSnapshot.html

Registering a snapshot works only for Linux/UNIX AMIs; although you can register a snapshot to create a Windows AMI, the AMI isn't launchable.

So, it looks like the cloning part is impossible for Windows, irregardless of same or different region. (Naturally I'd be delighted if someone knows different!)

Regarding moving from region to region, for Linux, this page shows a tool to do that (but the AMI image must be moved to S3 first). http://docs.amazonwebservices.com/AWSEC2/latest/CommandLineReference/ApiReference-cmd-MigrateImage.html

UPDATE: Regarding MigrateImage, I can't work out how to move the EBS snapshot image to S3, and vice versa. Also, https://forums.aws.amazon.com/thread.jspa?threadID=99335 says moving snapshot images to other regions cannot be done (as of Jul 2012).

Mar'13 UPDATE: Amazon have announced Amazon Machine Image Copy which allows copying AMIs from one region to another. The FAQ explicitly says you can copy Windows images (so presumably they will run!): http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/CopyingAMIs.html