There are some Chinese NetBeans Users who prefer to use NetBeans with English locale when his OS is Chinese. The simplest solution is to add “-Duser.language=en” to the jvm parameter, but NetBeans 5.5.1 seems not having a convenient way to add jvm parameter(such as providing some config file).
After Googling a lot I found that I can add “–locale en” to NetBeans’ startup shortcut command. This maybe is the “official” way to change a locale. But only with this added is not perfect, there are some UI element that remains to be Chinese even when most part of the UI is in English, where in this situation the Chinese characters just get messed up.
Incidentally, I found that changing the Look and Feel of NetBeans to Metal would give a workaround to the problem above. So the entire solution is to change the shortcut’s target from
"E:\Program Files\netbeans-5.5.1\bin\netbeans.exe"
to
"E:\Program Files\netbeans-5.5.1\bin\netbeans.exe" --locale en --laf javax.swing.plaf.metal.MetalLookAndFeel
where you should change the location of netbeans.exe to your own installation location.

screenshot:

netbeans_screenshot