High End P&S or Low End DSLR?

Hey everyone. I'm trying to get into real photography and need to pick a camera. Right now, I only have an old basic point and shoot that I bring with me on vacations and events. It has no manual mode so it doesn't really work well for learning to take serious photos.

I'm on a budget so I'm trying not to spend too much money. At the same time, I want something decent. One camera that looked appealing was the Canon S100. A lot of people referred to it as a "pocket DSLR" because it supposedly has a full range of manual settings and controls. However, I realize that I can get a low end DSLR for around the same price.

I have no experience with the S100 or any DSLRs. Is the S100 really as powerful as it sounds? I realize that if I go with that, I'll eventually have to get a real DSLR sometime down the road. But the portability sounds nice compared to having to carry around a bulky DSLR. And if I go with a lower end DSLR instead of the point and shoot, will there be a notable quality difference?

Anyway, as I said, I'm still a newbie when it comes to photography so all of my judgments could be totally wrong. Any guidance would be appreciated. Thanks!