True20 is OGL, so if you know d20, you can probably handle True20. If you have ever played or own either edition of Mutants & Masterminds, you will be familiar with the attack resolution and damage system.
True20 is more about the story than your stats, which is how a game like Star Wars should be played anyway.
If someone was interested in playing in such a game, I would be willing to help with any conversions, etc.