I don't know if anyone is really interested but I have migrated an old Ubuntu LAMP server running Sugarcrm 4.2.1 to a new box running FreeBSD 6.2 with Sugarcrm 4.5.1. While not a painless move/upgrade the result is well worth the effort and in hindsight really not that bad. The relevant pieces and parts are:

FreeBSD 6.2 Release
Apache 2.2.4
Bacula client 2.0.2( for daily backups to main server)
Mysql client and server 5.0.33
PHP5-5.2.1_2
Sugarcrm 4.5.1

All programs installed from the ports tree with the usual 'make install clean'

A little work is required in the php and httpd config files but all in all pretty straightforward and it seems to be working like a champ.