@Kurimono
The movies are worth at least one watch (I think) if you're curious about how they interpreted the book. But if you don't have that in mind, I don't think they're really worth watching. I don't remember the first one since I only saw it when it came out awhile ago but I remember the second wasn't that good and left a lot of blanks.
The third is regarded as the best so far. It has a darker feeling to it. It was the only Harry Potter movie that I felt I'd be willing to watch again. However, like the others, there were a lot of holes in the plot, unexplained things, and the order of events was waaaaaaaay off. Those who have seen the movie probably know what I'm talking about.
@shadowfox
Yes, the anime and manga are different. They do follow the same plot idea though; Keitaro and Naru trying to get into Tokyo University. But like DNAngel there are some differences. Example, that one guy, Koutaro I think his name is in the anime, doesn't appear at all in the manga.
Love the manga, not wild about the anime, especially the dubbed version. Listened to it dubbed for 3 seconds, switched back, and never switched back to dub for that series.