IMHO Vim and Gvim are hands down the best (most powerful, flexible, slimmest) editors for almost all platforms, win32 included.
I would not go back to anything else on Windows, and I've tried UltraEdit, ED for Windows, PE, and all the variants of notepad. Not to mention the various IDEs I'm forced to use for work.
But I would not advise a casual user to try and learn Vim if they had no previous Vi or unix experience. They wouldn't get value for the effort required to learn the commands etc.
And in case no one else mentions it, Vim is Charityware; if you like it you are encouraged to donate to help needy children in Uganda. Very nice.
http://vim.sourceforge.net