UFC.com allows you to watch UFC 100 on the Web in partnership with Yahoo.
Not free but a good solution if you cannot watch it on PPV TV or in a bar (List of all UFC 100 Authorized Locations on Joehandpromotions)
Saturday, July 11, 2009
It’s the biggest night in UFC history, and if you’re unable to watch this monumental event on Pay-Per-View television, you can purchase it for live viewing on Yahoo!Sports or on UFC.com. And if you buy the UFC 100 Pay-Per-View stream on UFC.com before 10pm ET on Friday, July 10th, you will receive exclusive access to Saturday’s unaired preliminary bouts, which will be available shortly after the conclusion of the live broadcast. For more details, click here