Welcome to Reaperland! :) No you can install the new version simply over the older one. If you want to be on the safe side, it's always a good idea to backup your user folders which sit in [XP] C:\Documents and Settings\Your_Account_Name\Application Data\REAPER [Vista] C:\USERS\<username>\AppData\Roaming\Reaper and contain your saved settings, track templates, FX chains and so on. But it's generally a safe process. Updating is very simple because it's exactly what you did on your first installation, except you don't have to point to a folder again because Reaper knows where it installed the first time.