Effective with this version, the minimum Windows OS that is now supported is Windows XP Service Pack 2. Windows 2000 support has been dropped.
The Release Notes are here and can be downloaded from their web site.
EDIT 18 Jun, 2012 - Changing version number from 2.10 to 2.10.1. - Edward
UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120604 Firefox/13.0 SeaMonkey/2.10