if anyone needs a cron script that does all kinds of tasks, i have one.
it does things like prune specific forums to specific age ( configurable )
prunes PMs to a specific age by Member groups ( configurable )
generates sitemap.xml and sitemap.xml.gz ( configurable )
and other crap.
you basically cron it and it is set to only be allowed to run from ( 127.0.0.1 - so no outside influences can intrude ).
PM me and i can provide it free..