(Since the payment options of Windows 8 and Windows Phone 8 are linked to your Microsoft Account, that gift card should work on both and maybe even the Xbox?)
Unfortunately for me, I didn't check the exact "terms and conditions" of that online contest... the code I got is only valid in the USA.
So I can't use it myself.
If you are an Windows 8/Windows Phone 8 user reading this, located in the USA. You can have it!
Send me an Email to "theone1893 @ outlook.com" (no spaces), the first one contacting me can have the gift card code.
*Just to be clear here (legally), this is not a contest nor am I selling anything. All I am doing is giving away something I don't need. If the code doesn't work for you either (for whatever reason), don't blame me :p
EditOk, that was fast... already got the first email.
I hope the code works for you, enjoy it Guillermo ;)