It's over Anakin. I have the high ground.
-Jedi Master Obi-Wan Kenobi


Setting: Mustafar
If only Anakin had heeded the words of his former friend and mentor. Well, fortunately, for the galaxy, he didn't or for all we know he would have succeeded in killing Obi-Wan. But the reality, well, as far as reality exists in the Star Wars universe goes, is that Anakin did not succeed, but instead got sliced and diced by Obi-Wan in one perfectly executed swift stroke that cut off all of his remaining limbs........

Several years earlier.....

Is the Dark Side Stronger? - Luke Skywalker
No. But, it is the most seductive. - Yoda

Setting: Naboo
Padawan learner Obi-Wan Kenobi has just witnessed his own master, Qui-Gon Jihn get struck down by a mysterious Sith whom they had been battling together for several minutes. After seeing his master fall to the ground by this tattooed villain in black, Kenobi started to feel enraged and when he had the next opportunity he attacked this menace with fury. Unfortunately, this Dark Force user knows perfectly well how to use that anger to his own advantage and during Obi-Wan's 60 second flow of anger he lost control during the fight and fell part way down a shaft also losing his lightsaber. However, while dangling there and hanging on for dear life, Obi-Wan calmed his mind and collected his thoughts becoming one with the Force. Putting all of his trust in something beyond himself and beyond attatchments, even beyond Qui-Gon's death, at that moment he was one with the Force and the Force guided him. Even though the Dark figure was several feet above him and by all logic clearly had the advantage, Kenobi quickly and surprisingly leapt several feet into the air reaching out with the Force for his dying master's lightsaber and then used it on his startled opponent, cutting him in half.

Conclusion
The two situations here described, Anakin and Obi-Wan on Mustafar and Obi-Wan and Darth Maul on Naboo all have one consistent message: It is the LIGHT side of the Force that is stronger, not the Dark side. Each time there is a battle, the Light side of the Force will overcome the obstacles. Now, some might argue that the Dark side is in fact stronger because of the Jedi purge. That's a good point, but in the grand scheme of things the Emperor was still defeated, Anakin still defeated Darth Vader, and Luke redeemed his father. The Force works on its own timetable. Also, notice the difference between these two situations. Anakin, using the Dark side fails to kill Obi-Wan who has the higher ground, and by this time Anakin is a skilled and at least war experienced Jedi Knight. Not to mention he was also the Chosen One, whereas Obi-Wan was just a Padawan learner who had never battled a Sith before and his opponent also had the higher ground. But Obi-Wan chose to use the Light side......and he won.

The Dark side is seductive, it is artifical, following its path will be to your own demise. But the Light side of the Force offers you strength, power, control, and eventually immortality when you become one with the Force.

As Always.

-The Star Wars Uncle