I have downloaded Windows 8 Consumer Preview ISO file and burnt it into a DVD. First thing the DVD doesn't boot and also when I try to run the setup from the DVD it asks me to clean up space in my C drive (in which 5 GB is free of 24 GB) because the Windows 8 need 16 GB space. But there is no option to install it in some other drive. I can't clean up the drive C, because it contains my current OS (Windows 7). Any kind of help would be appreciated.
Yes you can. On the main install screen, instead of choosing
Install Now you should choose
Install on another partition.
You can check the 3rd printscreen on this page.