On Drive letters. Your DVD/CD drive is probably D:
What I do is set the DVD/cd Drive to C + a few letters. to keep it out of the way (ie G:).
Then you can set your HDD to D:.
It's not a big deal if the CD/DVD drive is D and the HDD is E. Just change my example from D to E, so "E:\WhateverFolderNameYouWant" when installing a game on to the HDD. For example I have my steam as "D:\Steam" but it coud just as easily be "E:\Steam"