Hi.
For statistics I dont think there are many better freeware solutions than awstats, you can see it in use showing the stats from the projects sourceforge page here ->
http://awstats.sourceforge.net/cgi-bin/awstats.pl
Do you have any sort of hosting control panel on the server, cpanel, directadmin etc? What os is the box running, redhat9, RHEL, centos etc?
If you have a cpanel then awstats should be installed, if you have directadmin then there is an awstats plugin that can be installed and each user can install it on their domain with a single click. Spamassassin can be installed from both panels.
If you dont have a control panel then you will have to install it as root and configure it seperately for each domain and everytime you add a domain thereafter.
Let me know what your setup is and I'll let you know what has to be done and how long it would take.