You simply need to register...then listening to any shows from the database is free :
http://concerts.wolfgangsvault.com/Graham was renowned to record almost every concert he ever promoted...and even after 30-40 years, the sound is amazing (The Who, two Led Zeppelin shows from 1969, King Crimson from '69, Black Sabbath, Ten Years After...so much more).
Heck, I'm even listening to a Flock of Seagulls concert right now for god sakes. Definately check it out.? I believe it's legal because you can't save it on the computer. I would think so because his estate approved it I'm pretty sure.