I've been using Notepad2 as a light-weight replacement for the notepad.exe that comes with Windows for several years. Let's face it, the original notepad.exe falls short on many levels - no auto-tab, no multi-line tabbing/untabbing, poor line endings support to start... I've always felt it was inferior to even the old MS-DOS EDIT, which is a pretty sad statement. In comes Notepad2, fixing all of its shortcomings while remaining lightweight, and adding some other nice features as well.
It's always been somewhat of a pain to perform the replacement to Notepad2, since notepad.exe is considered a protected operating system file in XP and Windows 7. Fortunately, Kai Liu wrote an installer that does this for you automatically! I just learned about this this week and figured I would share.
To download the installer, just go to http://code.kliu.org/misc/notepad2/ and scroll to the bottom, "Custom Notepad2 Builds", for both 32-bit and 64-bit machines.