Just finished watching the DVD..it's been a few years and this just reinforces my opinion that this movie ROCKS.
Director Norman Jewison, who also produced, was years ahead of his time in forecasting the rise of the corporate state, designer drugs, the raising of athletes to heroic levels -- remember, this movie was released in 1975, and in many ways the world he portrayed is even closer today.
While it's fun to look back on the "futuristic" clothes and ancient computers, it's worth noting that this movie was made without blue-screen special effects -- no computer-generated stuff here. He used stuntmen to ride in the rollerball games.
The DVD includes a director's commentary with plenty of interesting details; for instance, the rollerball track was part of the Munich Olympic complex, and the big double-tower skyscraper in which James Caan's corporate overlords work was in fact the HQ for BMW!
Great, great movie.