I haven't used the f/1.4, but I've read that it's actually not quite as sharp as the f/1.8. It's certainly not as good value for money.
I just paid $40 a fantastic old Series E 50mm F/1.8 in good condition (they're all over the place on
eBay). It's a completely manual lens, so there's no metering or AF, but it works
great for portraits or any shots of slow or stationary subjects.
I have a D40, so I couldn't quite justify spending $150 for the new AF f/1.8D when I wouldn't be able to use the AF anyway. But, since you've got a D200, it's probably worth the extra cost for you to get the new version. I've read that the focus ring is underdamped, but since you can use AF, that's probably less of a matter for you.