You don't say if you have any data in the two partitions other than C: and D:, nor do you say how much total spare capacity you have, but if you move any data out of these two partitions, even if only temporarily, you could merge the two to give you three 'drives' - C:, D, and one of 215 Gb. The 14.75 Gb partition is of little use to man or beast ! Presumably this partition would be drive E:.
You can then decide, depending on how much spare space you have in C: and D;, whether to devote the whole of this partition to Win 8 or to split it into two more realistic sized partitions and still not exceed the four partition limit. To pull numbers out of thin air, two partitions of say 100 and 115 Gb would be more useful than what you have at the moment.
As you are probably well aware, the disc management tools under 'Computer' are sufficient for this task. Just one safety tip - back up your important data before you start doing this !