I have 100GB available on the C disk, but only 18GB left free. I was checking this out, and I realized that the D disk has 350GB available and it's completely empty. Can I use the D disk as the C disk, to save video/music/picture files? How can I transfer data from C to D, if D can be used to store those things? Will there be any conflict if, say, all my songs are on disk C and then I store one on disk D? If the memory gets filled on C, will it go to D automatically?

I am totally inept when it comes to technological details like this. Hopefully someone can help me out, I really would like to be able to store more movies on my computer without just one eating up 5% of my C disk.