Zak backed up his theory with some concrete numbers, maybe they were coincidence but it seems to make logical sense. We'll take it as true
lol.
I would personally stick my OS with my apps and my games because accessing files from different partitions slows it right down. It doesn't matter if the partition is 200Gb, it is still on the outside so it will always perform at above average speeds. I stick my media and files on the second parition because they are quite independent files, and I have a last partition to make sure my media doesn't get stored in the centre of the drive.