In LAMP stack, Red Hat’s community driven Linux distribution Fedora is quite popular.
But I do not understand why they are not upgrading MySQL server with latest Fedora-4. If you install Fedora-4 as server and also install MySQL server you will get MySQL-3.2.x.
While installing Sugar-4.x it requires MySQL-4.x. So first install MySQL 4.x in your Fedora machine.
With MySQL-4.x you can easily install Sugar-4.x. But be sure that while rebooting the machine MySQL-4.x get started not MySQL-3.x. Becuase Sugar-4.x does not complain about the MySQL version but it will not perform some quiries properly. The SQL quiries which conatins INNER JOIN statement will give error. (INNER JOIN was not supported by MySQL <4.x )