Wifite was designed for use with pentesting distributions of Linux, such as Kali Linux, Pentoo, BackBox; any Linux distributions with wireless drivers patched for injection. The script appears to also operate with Ubuntu 11/10, Debian 6, and Fedora 16.
Wifite must be run as root. This is required by the suite of programs it uses. Running downloaded scripts as root is a bad idea. I recommend using the Kali Linux bootable Live CD, a bootable USB stick (for persistent), or a virtual machine. Note that Virtual Machines cannot directly access hardware so a wireless USB dongle would be required.
Wifite assumes that you have a wireless card and the appropriate drivers that are patched for injection and promiscuous/monitor mode.