The Streets aren't really Grime, as he's from Birmingham. And it's only really Dizzee's first album that was really Grime. And that was where Grime was at a long time ago, and a fairly commercial version of it. There's nothing wrong with Grime going overground, but there's always loads going on under the surface.
This radio show, from last week, should give you a better idea of what it's all about, or any of the Grime podcasts from
Rinse.fm. Also, check the first Run the Road compilation.
You might want to check out Zed Bias's 'sound of pirates' to get an idea of how two-step, Grime and dubstep all relate to each other. Plus, it's a stone cold classic compilation. I tend to find that a lot of Americans have a hard time getting over the beats, which are often pretty different to American beats. Plus, a lot of Grime seemed to get sold in the states as a 'British crunk', which is bullshit.