You're saying that theBetaof OneNote 2007 says it needs someting SP2?
Possibly Windows XP SP2?
Did you install Windows XP SP2? After downloading it, you will need to
install it. The easier way to ensure you have the latest Service Packs and
other updates is to go to Windows Update:
http://update.microsoft.com/ and download the updates that website
recommends.
If your computer is up to date with all patches from that site, try
reinstalling OneNote 2007 again and feel free to ask about any additional
errors you get.