what do you mean by "raid it to the second drive"?
Softwareraid (md), Fakeraid (like most all onboard SATA Raidcontrollers, that are no "real" raidcontrollers) in combination with softwareraid, or real hardwareraid?
in the last case it is quite easy as you just tell your raidcontroller what to do, that's it. In case of md you just create raid partitions, combine them to a raid and "inside" you create your whatever filesystem. That also means you can deside what you want to "raid". So you could say you will hava a parition "storage" where you do store everything important, except OS stuff (as far as possible) and only this partition shall be raided, the other OS and SWAP partition, e.g. not.
I did it more easy to just create two raid 1 partitons with md, one for the whole OS and one for SWAP, as my personal experience showed that there is no real need (for my usecases) to have the stuff splitted in x partitions.
With the real hardware raid you may think about paritioning more freely, as the raidcontroller links all the selected disks no matter on the content. But be aware, that breaking the raid controller, you won't really be able to recover you data, except using the same raid controller. That's another positive thing about the software raid, just boot it up on another hw and that's it.