Loads more control. There's more to overclocking than just the CPU speed, the scaling governor is something like to change, as well as profiles. You can configure the CPU scaling so that it saves battery, but still goes faster when you need it to.
I would recommend
this kernel. Use v3.5, legend source based. It's near the bottom. I use the 787MHz version, some go higher. I would recommend 787MHz as a good starting point. The good thing about v3.5 is that it has the interactive scaling governor, which strikes a good balance between battery life and speed.
Now, I'm sorry to say it, but you're gonna need to use
Google to find out more about this, it's all out there. But if you don't want to then use the kernel I recommended and don't bother with setCPU