Windows7 & Media Direct -Inspiron 1525

Hello mates,
I am thinking to upgrade my vista to windows 7. So, I have some queries which bothering me. Like do i need to format whole hard disk or only c drive ? I want my media direct as it was . So i dont want to mess media direct partition. I just want to format my C drive and install windows 7 over there. Suppose i format only C drive and install windows 7 on C drive,then do i need to do anything extra except installing media direct in windows 7 or do i have to format whole hard disk and i have to first wipe off full hard disk and let the media direct dvd make there own space ?
Please help and also tell me what other drivers needed for windows 7 i keep them handy.
Thanks...

PS:- Currently I have 2 partition, C have vista installed and D i use as my stuffs drive. I dont want to touch my D drive in formating and want media direct to work on windows 7. "I am using vista on C drive with media direct and D as my stuff drive". I just want to replace my OS and all thing remain same as it is.

 

You do not need to format anything to install Windows 7. It will move your old files into a "Windows (old)" folder IIRC.