From my experience, only MS apps send stuff to C:/ by default. Most applications, even dated, allow us to pick where it goes. It should be C:/ though or what's the point? The Documents part is what matters. Programs don't take up a lot of space. What may hang over is the Users directory and it's defaults.
Music? Point it to another drive with a right click. It's Win7...it's there, you can do it, and we just struggle with stuff written for XP and prior. My Documents aren't on C...yours don't have to be either. Put them where you want, and show Windows what you're thinking.