Here are some insights you might want to know:
Extra small instances might not be included in your free Azure account.
David Pallmann was the first to notice that some of the special Azure offers (like the MSDN one) actually have some small letters:
**Extra small compute instances are available in beta and are billed separately from other compute instance sizes.
This practically means you pay for these instances from day 1! Here is my account:
So you should check your account details and determine if extra small instances work for you.
I also recommend you check out David's Hidden Costs in the Cloud series which has some important insights.
Hot news: Azure trial with extra small instances
A few days ago Microsoft has started to offer an introductory offer which includes 750 free monthly hours of x-small instances (until June). Check it out.
Also thanks to David Makogon I've fixed an error in the config sample to configure extra small instances.