I had EXACTLY the same problem when I migrated from my Palm Tungsten E2 to the Treo700w. I'm using PhatNotes (I don't have a URL handy but Google it and it comes right up). They offer 2 or 3 versions of the software from a basic one to a really fancy notes tool (but it operates outside of Outlook which is my "home base" and I didn't need the extra functionality and required sync). I'm using the basic version and it's fitting the bill nicely. The synchronization is embedded in ActiveSync so it requires no extra effort. Once I decided I liked it I deleted all of the notes in the Windows Mobile application and turned off the sync to it, so now it's Outlook or PhatNotes only - just simplified things for me a little.
Like most good software, they offer a trial period so download it and try it out. Good luck!