I want to install 2.0.17 and have an existing database (the version of PHPBB I’m using is probably 3 years old now). Is there a way that I can install 2.0.17 but use the same database I have now? Do I need to rename the database or is it a matter of editing one of the phpbb files? Thanks in advance!!
phpbb.com/kb/article.php?article_id=271
phpbb.com/support/guide/#section2_4_2
Basically you upload the new version over the old one (and save the config.php first). Then run a program that finishes the upgrade (and putting back the config.php file sometime).
The first link is pretty thurough.
Thank you thank you thank you!! 
Oh, and since you’re doing an upgrade you would use the: phpBB 2.0.17 [ Changed Files Only ] package.
But my version is ancient… I first installed it almost 3 years ago. Wouldn’t it better to start all over? I did a search and was trying to find some of Goose Egg’s posts. I thought he’d done a new install at one point, maybe even more than once.
I haven’t reviewed the change file documents for the latest versions of phpBB.
In the past, I would start with the original database and then run each succeeding change script. I believe the script is changing the data structure, so moving up progressively sounds necessary (there may be some change scripts that allow your to leap frog up - for example, v 2.0.11 was a very popular and stable version, so there could be a leap frog script from 2.0.11 to 2.0.17)
To find old upgrade scripts, I go to phpBBhacks.com - they maintain a section with all of the phpBB scripts and upgrade scripts. I don’t think phpBB even has this
Very helpful, thanks guys.
Update: I did it!
Followed the directions at the link provided by MT here:
phpbb.com/kb/article.php?article_id=271
Thanks guys!! Now if only I had time to spare so I could play with some mods…