If you have a $400 budget (I see that from the Schwinn) I would get an entry level Specialized Hardrock. I differ from most other people here who will tell you to buy a used bike. I prefer a bike that I know has not been ridden by someone else and hence has no worn out components or secretly broken parts. It's ridiculous, some people come here saying they have a $2,000 budget, and they're still told they're better off buying used ! It's crazy. Buy a new quality bike.

P.S. Flame on. I stand behind my point.