Before Star Trek, even before Lost In Space there was "The Doctor."
Dr. Who was first produced by The British Broadcasting Company 1963 and aired continuously with new episodes until 1989. After 1989, there have been radio programs; publications, a TV movie, and flash animated stories.
This makes Dr. Who unquestionably the longest running science fiction program in broadcast history. The BBC has done a great job of maintaining an active Dr. Who site. Another good resource is Outpost Gallifrey One.
U.S. fans of the TARDIS may have gotten hooked on episodes that aired on local public television stations. The Doctor encountered aliens, monsters, new worlds and a steady stream of companions. The most enduring? K-9 a robotic dog.
To start you properly on the road to Gallifrey there is A Brief History Of Time (Travel) - a fan based site that does a nice job of getting you up to speed on the history of the show. Then take a side trip to the Dr. Who Information Network which is devoted to all things relating to Dr. Who and the fans that support the program.
The Dr. Who Image Archives has 7,000 plus images of the world(s) of The Doctor. For a historical look at over 40 years of writing and publications about the series, visit Cuttings Archive.
And they say Star Trek fans are in too deep.
Well, you can't keep a good (or bad) Time Lord down for long. The British Broadcasting Company is producing new episodes of Dr. Who. That is the good news. If you live near the Canadian border or can get Canadian Broadcasting on satellite it is even better news. The CBC has video trailers in QuickTime and Windows Media format.
The bad news is that those living in the U.S. can't view the new episodes. I'm thinking if all the U.S. Who-Heads wrote their local PBS station asking very nicely if they would air the new series, with an implied kickback at fundraising time, we could start America on the path of rejoining the world community.