EditPlus is by far the most used application on my computer. It's very, very fast, and very easy to use. The syntax highlighting is a dream for programming.
Another one you could try that doesn't have syntax highlighting, but is free (well it says send a postcard if you use it) is EditPad.
http://www.jgsoft.com
It takes a while (read: a couple seconds instead of instant like Editplus) to load up, but it has a nifty systray icon (instead of taskbar - but it's an option, you can turn it either way), and line numbers...
Er.. WOW I just went to EditPad's site, and they have now split it into two versions (lite and pro) - pro has syntax highlighting, and a bunch of other stuff, but costs money. You can still get "classic" for free though, with all the features I described above.