Undead and Souls

[Xilodel]

So I'm trying to write up a cohesive setting for my ongoing campaign, partly for my own amusement and partly because it will make it easier to keep things homogenous from session to session. I was working on races and monsters, and I've made it to the session on undead.

Now, I hailed from a largely D&D 3.5 background before headed to GURPS, and my campaign setting was originally written for Iron Heroes, so the D&D influence is still pretty strong. I went back to a few of my old sourcebooks to see how they handled undead, and one of the books mentioned that undead Incarnists "cannot bind chakras to their soul", presumably because they don't have one.

Now, for mindless undead like zombies and vampiric spawn that are nothing more than extensions of their creators' wills, I can understand that logic. But what about intelligent undead that retain their personalities? Liches and vampire lords are the first things that come to mind, but even things like Wights and Mhorgs (sp?) retain their human intelligence and personas when they make the transition to unlife.

I'm thinking about making it so non-sapient undead are simply bodies animated by fell magic (no soul required), but any undead with an IQ of more than 6 and a definitive personality retains their soul until true death.

I understand this is mostly a matter of campaign flavor, but I'm curious to see how the rest of the forum deals with the issue (assuming you guys have given it any thought).