It is a perfectly legal version of Snow Leopard, but I put it inside of my MacBook White, and it just spits it back out after trying to spin up. The drive reads my Leopard as well as my MS Office 2008 Student for Mac just fine, it just hates Snow Leopard. Yet the same disc works just fine inside of an alu. MacBook. Any ideas? Should I take it into Apple, and have them put it on using one of their drives? Sorry I can't type right right now, this is just frustrating.