Microsoft has been offering Skydrive for over a year now. Google Drive has nothing to do with skydrive. Infact they've been offering 25GBs to everyone who subscribes up unitl Google Drive came out. Now its 7 GB for new users and 25 GB for old users if they claim in before May.
Google Drive is only 5 GB free so Microsoft probably realized they've been giving away more than they have to.