I'm running a much older version of ECT (6.4, generic version). My site is very simple and there's probably not many new features I'd be interested in, but I know it's probably best to upgrade mainly for security issues. I'm worried about how much of a headache it will be after the upgrade. If I upgrade to the newest version, will my basic configuration and current settings remain the same?

Hi, here is some good info - https://www.ecommercetemplates.com/tutorials/#update

Updating does not change the layout of your design and "front end" customizations.
If you have made edits to the files in the vsadmin folder, other than the includes, and db_conn_open files, then that will be overwritten. Most users do not make edits to those files.

You will liekly need to address the following on this update - https://www.ecommercetemplates.com/support/topic.asp?TOPIC_ID=107040

ECT does provide a low cost service to apply the update for you if needed.

Thanks,
David