Great timing for this topic.
The reason you see some odd gaps in the topic chronology is that the automatic archive in the original (2003) forum software grabbed topics that hadn't received an update in X days and moved them to the archive. Since some very old topics were still active, they didn't get moved to the archive, while some newer topics did.
Last night, I wrote the scripts necessary to migrate the archived topics from the original forum to the new forum software. I'm testing them in my local dev environment now.
So, with the launch of the new software (testing is ongoing...more news soon), we should have a complete catalog of ot.com posts going all the way to March 10, 2003.