First off I would avoid using WMP 10 for DVD playback. There are much better options and free ones to boot such as VLC. But if that's not an option in your situation I would probably choose InterVideo's only because I'm familiar with their products and have had great success with them as well as their customer support.
Also, if you do want to go the professional player route and you're going to lay down $20 bucks for a plugin personally I would A) kick in the extra $30 and buy the full-fledged PowerDVD or WinDVD software suite or B) if you have the extra dough up to ~$100 or so, go the hardware route like Sigma Designs X-Card (hardware decoder card with TV out and loopback).
Maine has a good swing for a pitcher but on anything that moves, he has no chance. And if it's a fastball, it has to be up in the zone. Basically, the pitcher has to hit his bat. - Mike Pelfrey