Below is a list of Operating Systems I have used;

FreeDOS

MS-DOS 6.22

MS Windows 3.x

MS Windows 9x (including ME)

MS Windows 2000

MS Windows XP

Minix 3

Trinity Rescue Kit

Gentoo Linux

Mandrake/Mandriva Linux

Ubuntu

Knoppix

Debian

Fedora

Solaris

Syllable

FreeBSD

NetBSD

OpenBSD

Apple Macintosh OS

I will of course add more as I use more. The ones listed in bold I have extensive experience in, I have experience in installing all of the above