Kernels default to stock speed until you install SetCPU. So even if you get a 1.3ghz kernel, without SetCPU it will run stock speed.
If you don't want to pay, the developer gives SetCPU away for free in a thread on xda-developers. Go have a look.
And yeah you can set the max/min speed that it runs while you use it, while its sleeping, charging, speed when it gets too hot, you can even set it to slow down when your battery reaches certain percentages.
It's pretty nice.