i figured this out the other day, and i have tested it, and verify that it indeed does work...here's how it goes...
you must use internet explorer
https://ssl.bing.com/rewards/signup/SEGetStarted?form=pgbar2&publ=BINGCOM&crea=TEXT_MRWHPG_Rewards_LaunchPS0929_BingHP4_0#fbid=Z4N3Lam-mZ4&crea=TEXT_MRWHPG_Rewards_LaunchPS0929_BingHP4_0&wom=falsego to that link, sign up for bing rewards preview, and install the bing search bar rewards bar into your internet explorer...
every day type in 50 random searches, this will get you 10 points per day.
there are offers that change every few days, that give you 3 points each to simply click on a link each...
you start with 250 points, which is enough to buy 200 microsoft points(100 points per 100 points).
click the rewards button, then the offers section, then redeem points to get to the reward choice section....search for microsoft and pick the 100 points...then they email you the code within a day or so
i've gotten 300 points so far and i started this weekend