In jQuery 1.4 there were some API changes that breaks jQuery UI 1.7.2 and earlier. jQuery 1.7.3 is the lowest version that supports jQuery 1.4 and up.
Just my luck, the website I was trying to update used jQuery v1.3.2 and UI v1.7.2. The site used jQuery UI intensively throughout the site so upgrading to the latest jQuery was not feasible for what I had to do. Instead, since I was creating a new page, I decided to use the newest version of jQuery for this page only. If I ever need to use both jQuery versions on one page, I can always use noConflict like how this guy says.
As a side note, jQuery UI Tabs was redesigned in v1.9 but will still support v1.8 API until v2.0.
To get a full list of legacy jQuery downloads, go to google code: http://code.google.com/p/jqueryjs/downloads/list (newer versions are on github)
To get a full list of jQuery UI downloads, go to google code: http://code.google.com/p/jquery-ui/downloads/list
To get a history of jQuery UI releases, go to their blog: http://blog.jqueryui.com/