Earlier this week, I had my first experience upgrading a site from Drupal 5 to Drupal 6. I was already using Drupal 6 for new websites and was eager to embrace the benefits on the older websites that I support. I didn't think it would be too awful to upgrade since I've stayed conservative with all the modules that I've chosen and (supposedly) all of them had supported upgrade paths.
I love the computed field module. It's remarkably useful for a wide variety of applications where you want to use a tiny bit of PHP in a content type but don't want to write a whole module to do it.
Until this week, I've generally been using it to calculate things such as the closed date of a work order (based on whenever the 'closed' field is checked) or for simple email notifications.
Note: if you're following these instructions make sure to replace everything with your own site names and paths.
We've been using virtual hosts in multisite installations for almost 2 years now. Pretty straightforward - request the DNS address. Add a couple lines to httpd.conf:
DocumentRoot "YOUR_FILEPATH_TO_DRUPAL_INSTALL"