The greatest thing about the game is that it's HUGE! I've been playing one character for a while now, but I know if I play another character for a while, I'll have a completely different gaming experience. The world and magic system is just so interesting to me, that's why I'd like to see it in d20 form.
I'm just gonna keep using this thread to rattle of ideas I've had about a conversion. Tell me what you think.
Attributes:
Strength - as in PHB
Endurance - as Con in PHB
Agility - as Dex in PHB
Speed - Determines landspeed like this: each bonus adds 5' to a person's base land speed, each penalty subracts 5'. i.e. Speed 14 = movement of 40 feet (yes, I'm assuming they're medium sized, but there's no halflings in Morrowwind, so there.

) Also, might this determine your bonus to unarmed attacks and shortblades - if so, then Endurance would effect your spear attacks...
Intelligence - Used to determine the magic points and spell bonuses (Unearthed Arcana Variant?), otherwise functions like as in PHB
Willpower - As Wis in PHB
Personality - As Cha in PHB
Luck - Hard to know if I should include this one. My latest thoughts are this: each skill can have a critical failure or success (1 or 20 respectively) - after one is rolled, a second role is made to determine degree of failure or sucess, the luck bonus or penalty applies to this roll. i.e. Luck 14 character tries to unlock a chest DC 25 (let's say he has a +6 to security checks) and rolls a natural 20 (26 total), critical success. He rolls a second roll, this time applying his luck bonus (or penalty) to the roll. Character rolls a 17 +6(security) +2(luck) = 25! The DM would determine what happened, but in this case I could, for example, say that the character did so well picking the chest, that he did so as a free action. I think this mechanic captures what the luck skill does in the actual game - always in the background, but always a factor.
OK. Enough rambling for now. I'll try to come up with some more ideas to bounce around.