Should be enough.
You lose 9GB to formatting, then ~20GB for the OS.
Also if you have a large Steam library, it will have to go on the HDD. You cant designate where each game goes when you use Steam, it will just install to where Steam itself is located. You have to install Steam to the HDD.
In general its better to have games on the HDD, they dont benefit much except for load times.
Dont forget to move the Page File to the HDD, that will get you back the same amount of storage as your physical RAM.