C: but understand you lose everything on that partition,not completely true because there are still things you can recover but what is overwritten is lost.
And yes,make one partition of it because that 39 Mb and 8 Mb is of no use other ways.
In fact,I do recommend people to make at least 2 partitions,one which hold your Operating system and one for pictures-Music and so.
Why?
If you have to reinstall windows you would not have to back up all that stuff which makes reinstalling a lot less a hassle.
Since your disk is a big one I would do 60-40% or so,and you could also move your virtual memory to that other partition,which is almost for sure on a different platter so less seek time when your disk is busy looking for other stuff.
One more thing,you can always get one partition more by getting the program partitionMagic,it does the trick without losing any data!!!!
Oh yeah,many people reinstall windows but most people don't know anything about real!!!! cleaning,use a program which cleans your register and after that defrags that register,a lot less problems then and it makes your system much faster,most of the times no need to reinstall.