Well Poo, other than work for Bush, Rummy has done quite a lot as his DOD bio shows. You seem to have left out a few details (not suprisingly given your track record).
"Mr. Rumsfeld resigned from Congress in 1969 during his fourth term to join the President's Cabinet. From 1969 to 1970, he served as Director of the Office of Economic Opportunity and Assistant to the President. From 1971 to 1972, he was Counsellor to the President and Director of the Economic Stabilization Program. In 1973, he left Washington, DC, to serve as U.S. Ambassador to the North Atlantic Treaty Organization (NATO) in Brussels, Belgium (1973-1974).
In August 1974, he was called back to Washington, DC, to serve as Chairman of the transition to the Presidency of Gerald R. Ford. He then became Chief of Staff of the White House and a member of the President's Cabinet (1974-1975). He served as the 13th U.S. Secretary of Defense, the youngest in the country's history (1975-1977). "
http://www.defenselink.mil/bios/secdef_bio.htmlI should add the Rummy retired as a Captain (Reserve) and was an aviator. See the bio for more.
The specific period Willie Green cited was 1989-1992, and that was the only defense-related post he held during those particular years.