Original sentence: VirtualBox by innotek is a commercial and proprietary (with a limited GPLed version) x86 virtualizer for Linux, Mac OS (beta version) and Windows 32-bit hosts supporting FreeBSD, Linux, OpenBSD, OS/2 Warp and Windows as guest operating systems
Edited sentence: VirtualBox by innotek is a commercial and proprietary (with a limited GPLed version) x86 virtualizer for Windows, Mac OS (beta version) and Linux 32-bit hosts supporting Windows, Linux 2.x, OS/2 Warp, OpenBSD and FreeBSD as guest operating systems