If you decide you can't live without the three games listed above, and you purchase them during the month of March, Microsoft will reward you with 400 MS points! That's enough to buy a game in the "Game Room." (The Game Room itself will be a free application download)
Along with the free points, Microsoft is offering a free, extra month of Gold Membership to people who purchase these three games and are already gold subscribers. If you are not a gold member (yeah baby), then you will have the chance to play all three games on Xbox Live for free during the weekend of March 26th (provided you purchased them).
You can qualify for these incentives any time during the month of March by purchasing all three games and downloading the free Game Room application.