u r welcome
yes, u can make changes after ur computer is setup..just download any partition manager....i am using a full version of Partition Magic. Trial versions are available on the internet for free but they wont work for you. you have to purchase or just download the full version from torrent (as i did) or from any other (crack) website for FREE.

A: and B: are ur FD drive(floppy drives)
C: D: E: F: . . . . are your hard disk drives + removable storage devices.

And yes you can use your E: drive to store movies+your downloads.
I do recommend you to use D: or E: to store your downloads...its much reliable....you dont have to cry if your windows corrupt's or crashes due to a technical fault or due to viruses