Few Months ago, David had a presentation about subversion. For all text files he has used a notepad2. After installing it at home and using this tiny software, i eventually used it instead of notepad.
Yes, notepad is the best plain editor, i known 
, no doubt there. But still, we are living in a modern age, so notepad2 is the best replacement for notepad and whats the best, it's totaly free (in my opinion). Well, there was a instruction for Windows XP on how to replace Notepad with Notepad2 (by Roland Weight).
Month ago, i installed newer version of Windows (Vista) and try the same procedure. After 10 minutes, i give it up. UAC has maked my hair gray.
But after googling a little, i found this great article about replacing it in Vista. So, if you stick with the procedure, nothing could go wrong. Except some bluescreen.