first heard H^2G^2 on radio, and those who read the books. There's nothing quite like first hearing it over the radio, or a stereo (the first version I had was a trio of records from Britain). H^2G^2 was the first radio comedy series created in full stereo by the BBC Radiophonics Workshop and on a walkman in stereo it is mind-blowing in that ancient phrase. The Audio Tape was available and was a present for my son, Then the CD and MP3 versions were available and were presents for me. The MP3 version has lots of commentary and was released before Adams untimely death of natural causes at age 52. Adams was a friend of the members of Pink Floyd and the little blip on the record about the loudest rock band in the history of history itself is a tribute to them: Disaster Area, and their lead singer Hotblack Desiato who is spending a year dead for tax purposes.
I credit NPR for permanently frying my synapses immediately before leaving for Canada, where the series started all over again almost the day we arrived.
I also found the vinyl version here which is different from the radio version. I actually sent the tear out leaf at the back of the first edition of the novel in order to get volume 1 of the series. It has been a permanent bond between myself and my 23 year old son ever since. My wife just shakes her head in bewilderment to which periodically I whisper "Good".
I am less a fan of the non-Douglas Adams versions, but perhaps that means I'm growing old. I used to have fun identifying all the bits of records used in the original series like Terry Riley, A Rainbow in Curved Air and various other bits, and it is to that that I credit my son's virtually perfect taste in music, unbiased though I may be.
Actually my son walks the tightrope of musical tastes between us extremely well, liking the marginally likeable pop, and loving the Indie scene which has always been my personal interest.