Robert is trying to install Windows 7 onto a MacBook Air, but he gets an error with BootCamp that the partition isn't NTFS. Leo says that one known problem is with the Mac Fusion Drive. If it's just an SSD however, it should work. He'll have to format the disc in Windows Installer, not BootCamp. Apple doesn't do NTFS, it just partitions the hard drive. Let Windows installer do the formatting of NTFS during the installation. Press "O" for options. He'll also need the Apple drivers.
He can use both. It really depends on how much hard drive space he wants to dedicate to Windows. Bootcamp will take the hard drive and divide it into two partitions -- one will run Mac OS X, and the other will run Windows. When he starts up, he can choose whether it will be a Windows or Mac machine. When he boots into Windows, it is a full Windows computer and runs at full speed. All the memory and processing speed is devoted to Windows.