mh I'm on my way to implement monitoring of my serverfarm with zabbix. 
I think i can post a howto afterwords.
Zabbix is a really nice looking monitoring & reporting application. 
It has its own daemon and is really fast. 
If you're going to use munin with more than 5 hosts and 10graphs each then a small server is generating every 5 minutes 50 graphs which takes a few minutes (between 2-4) so the system will get very busy 
 
Thats why i was looking for alternatives - and zabbix can use a gsm-modem or other services to notify you, if something goes wrong - and thats what's really cool on it