friend of mine's crashed at least 4 times, and every time they gave him all his credits the things he purchased from his old HDD, he was then able to download the previously purchased material onto his new hard drive free because he had already bought them before. So he basically quadrupled all his credits and was able to buy just about anything they came out with on Xbox live. I tend to think he is making his xbox die on purpose because they keep giving him free credits.
Imagine the first round you get all the credits you spent plus the stuff you downloaded(no charge). You get to use those free credits for new stuff to download.
Next go round you get ALLLl the credits you spent(doubled from previous go round) and all the product you bought prior is re downloaded(including the stuff from the free credits).
This happened 4 freakin times Which is almost like 32 times as many credits as he actually bought.(including all the product he downloaded)