My latest obsession is RuneQuest (of the Mongoose variety as it's the most likely of the lot to be found in the three local Half Price Books and the used game shop).
I think I'm doing it wrong. I ran one adventure using my general system of choice (GURPS) but it's a little complicated for a newbie GM to teach to four people who have never heard of it.
I wanted something easier so, in my brilliance, I decided to read the Ars Magica books a coworker gave me. The one-shot adventure I read said character creation would take four hours and you should instead use thirty minutes to hand out and explain the packaged pre-gens. I finally decided to move on when I realized that everyone probably doesn't want to play a mage and everyone probably doesn't want to have to create multiple characters.
That brings me to RuneQuest. I finally picked up the core book after buying about eight others. I haven't given it a cover-to-cover reading yet (I'm in the process) but it should be just close enough to D&D for them to be somewhat comfortable - stats are mostly 4d6b3, except for Int and Size (2d6+3 but I'll probably do 3d6b2 + 3 just to keep with the roll and keep theme), a big equipment list, and two books of monsters that I've found thus far. The only sticking point I've found thus far might be character advancement being skill-based. I'm not sure if base attributes can ever be raised and I don't think characters can ever gain more hit points.
But hey, the character sheets look nice and will likely force me to throw out my multifunction inkjet and get a laser printer of some type.