I have been 'playing' around with computer systems since the days before Windows came out, so I am very familiar with the likes of MS-DOS.  My first computer was the Amstrad PC (which is going way back, considering that I don't think Amstrad has sold computers for a very long time).
I am fully familiar with nearly all versions of Windows, from Windows 95, right up to present day operating systems.
I have a wide range of experience, both on a personal and professional level, and have dealt with a wide variety of IT problems (both hardware and software).
My general 'skillset' is:

MS-DOS, Windows 9x, 2000, XP, NT, Windows 2000/2003 Server, MS Office, Networks