Forrest Gump would say Windows Vista is like a box of chocolates; you never know what you're gonna get. I like some of its features and its looks, but other things have me spitting mad. For example, the spotty support for drivers.
Since I'd updated my drivers twice (once from Windows, then from nVidida) the driver rollback option was out. Instead, I found an install file for the original video drivers I had on the computer. After uninstalling the new and reinstalling the old, I am back in Lord of the Rings Online. I won't pretend to be technical enough to understand why, but my FPS actually increased by five over what it was originally. /shrug
P.S. Check out Random Ogre Thoughts. Good rants on a variety of MMO related topics. His post on Quality struck a chord with me. Another post to read is his What Do I Want in a MMO? He commented with the idea of rolling back my drivers, which put me on the path that led to the solution. So thanks!