Trying to install Windows 7 in VirtualBox from Windows 7 DVD but won't install. Does it only install from a ISO file or something?
What is the actual errors you are getting?
Virtual Box should act pretty much like a physical machine and there should be little to no difference.
It can mount either a physical disk or an ISO of Windows.
I would just double check the basics:
If none of these help, please state the actual problem you have.