Upgrade Hard Drive

[xk220]

I have a ew pc that has a 40gig drive - 10 is in "C" drive the remaining is in "D" drive- I have virtually used most of "C" only1.91gig remaining + 14gig in "D" ,due to my music collection. I want to add a new hard drive alongside the existing set up - which I know how to do. The question is will I be able to add memory to the "C" when the new drive is added or will the new drive just appear as a seperate drive - if it makes a difference my pc has SATA HD? I am also adding an external HDD as well