description and video upload by seanwolcott
From the Wikipedia entry:
The "Dr. Who" theme music was created in 1963, composed by Ron Grainer and "realised" with electronics by Delia Derbyshire of the BBC Radioponic Workshop. The theme was one of the first electronic music signature tunes for television. Its haunting and ethereal sound has become as indelibly associated with the programme as the TARDIS or the Daleks, and the theme has endured over four decades.
For Season 18, Radiophonic Workshop staffer Peter Howell provided a new arrangement performed on analogue synthesisers, giving a more dynamic and glossy, but less haunting feel. Its bassline was created on a Yamaha CS-80 synthesiser, with added echo. The main melody was played on an ARP Odyssey. The 1980 arrangement added the sting to the opening theme as well, while the "middle eight" was included in the closing theme arrangement of all episodes. Howell's theme is in the key of F# minor.
And from uploader royalmarriage:
Mixing the themes together must be a popular thing to do among Dr. Who-iphiles, with the official BBC site offering its own theme mixer.