1: Go to www.bing.com/rewards/
2: Click Try it now." free " and create an account.
3: After you made an account go to http://www.pogocheats.net/bing-rewards-bot/
4: Make sure you set the search count to 30, then click Start Searchin!!
This gives you 15 credits a day. if not you reach GOLD status (30 credits a day!).
5) Do this everyday until you reach 475 credits. Then REDEEM the 400 MSP.
I know this method it not fully for free because you gonna spend sometime on it but you can keep doing this again and again and i would rater spend my time than my money!
Best Regrats
- Me!