One thing I change everytime I have a new userdir for NetBeans is the code completion sensitivity. I think it's just much more productive to use the case insensitive code completion - typing the case correctly is another thing I need to think of when writing code. This is especially useful when I write classes like StringTokenizer, BufferedReader, etc. You can turn off the sensitivity here:
I wonder if there is anyone who actually needs the case sensitivity. As far as I know in NetBeans 6.0 we plan to switch this option to insensitive by default.