I was thinking about the matter of converting from one system to another. It's true that I like GURPS, but I also like D&D. So why convert Greyhawk, already well-established as a D&D property, with D&D stats ready and waiting, into GURPS, which is a lot of effort? I have a number of reasons, some of which I want to mention here.
First, there's the matter of tone. D&D has a tendency toward a particular type of heroic, "cinematic" play that follows certain narrative conventions. GURPS, on the other hand, works toward a different style, even when it is used with "cinematic" optional rules. Think of it as the difference between, on the one hand, Robert E. Howard, and J.R.R. Tolkien on the other. That's not to say that either author represents either rule set, only that there is clearly a difference in tone.
Second, by playing with the stat blocks, I hope to illuminate the ways in which each rule set abstracts certain aspects of the fictional reality they represent. That is, I can look at the factors which make up "hit points" in D&D, but are detailed out in GURPS. Similarly, social structures are abstracted into specific modifiers in GURPS, but are dealt with more subtly in D&D, mainly through adjudication. Mostly, though, I'm trying to work out what a "level" is, what "hit points" are, and so on in D&D. By doing so, I hope to improve my D&D games.
Next, sometimes it's easier to get a game together if it has a particular premise. The idea of GURPS Greyhawk is just plain interesting to some people, and should gather an actual gaming group. I would like that, actually, though I'm pretty sure that my next face-to-face group is going to focus on Swords & Wizardy: Whitebox.
Also, with luck, I'll get some of you commenting on the entries, and providing critiques and suggestions for various matters.
Finally, one of the things about GURPS (or any rule set really, but GURPS specifically) is that it helps to practice using its rules in various ways. This is sometimes called "system mastery", and is useful when running just about any game, not to mention when playing some of them. By working out conversions (and the project as I conceive it is extensive - I hope to eventually provide a stat block for at least every entry on every encounter table in the Greyhawk boxed set and the DMG, for instance), I get to practice using GURPS, which is good for my purposes.
Oh, yeah. And why Greyhawk, specifically? That's easy. Greyhawk was the first fantasy game world I ever read about. I owned the folio edition (the original one I owned has since been destroyed, but I have replaced it, as well as getting a copy of the boxed set). So, it's pretty much nostalgia. However, there are aspects of the Flanaess that are especially interesting to me, such as the general atmosphere of medieval Europe combined with fantasy elements in a particular way. Greyhawk is prototypical of fantasy gaming worlds, and has only rarely been equaled.