Hard drive partitioning is done before system setup. you can no longer alter the size allocated on each partition once you had done system setup but you can always reformat any partition safely without causing damage to the other partition. If you are willing to reformat the entire hard drive you can always do so just make sure you have all the necessary installation software including drivers. Ideally allocate only 10GB for the system drive (C:). and all other applications to the other partitions. This would isolate your system drive from all other applications and will definitely run better. Occasionally run defrag on all partitions especially when you regularly download and install applications.