Skill Based System.

[Diggles]

Yeah, unlearning is the thing I'm not sure how to do.

I don't entirely like the Planetside idea. I don't think it makes much sense for an RPG like we've been talking about.

(edit: Veraphim beat me to it.)
I think what I'd like to do is that you have, say, 10 "foci", or skills you are focusing on and thus increasing points in. If sword is one of your foci then as you swing your sword, you gain sword skill. Points will go into your foci either from your pool of unspent points OR from your unfocused skills.

So lets say you have all 1000 points invested but you want to learn Evocation. You must select Evocation as a focus and you must also choose at least one other skill to remove your focus from. So you de-select sword and select evocation. As you cast fireballs, you gain evocation at the expense of sword skills.

You still HAVE sword skill and if you pick up a sword you can still swing it with whatever skill you have left, but you won't gain any skill until you re-select it as a focus and then deselect something to feed it points.

I like this way because it doesnt gimp you when you want to relearn. In SWG, as soon as you drop the master box, you lose access to a ton of your most power skills, while you are ranking up another tree.