A relaunch to promote a new interface is kind of odd. A relaunch should be a major change in hardware or functionality.
Also, giving 6 free Xbox original titles screws over all 360 users without a hard drive. Nice way to celebrate reaching the $199 price point, by giving away something those new users cannot use.
What MS should do is relaunch the 360 with a redesigned slim, cooler, quieter console and eliminate all live fees. Focus the relaunch of casual gaming and start a giant casual marketing push for the Holidays.