Redundant log settings between Drupal and Apache
There's a good drupal.org page on how to switch from dblog to syslog module: see Syslog: using the operating system's logging facility.  


  "Because the Database logging module writes logs to the database it can
  slow down the website. By using Syslog you can improve the performance
  of the site."


Combine that with a log rotation strategy of some sort.  And then you'll soon be knee-deep in sysadmin-esque territories.  But probably not neck-deep though if you catch my drift.  Lots of good documentation online for log rotation.  Also, I've not done this on D6, only D7, but that page referenced above does have instructions for D6.