I use "DVDFab" which works pretty dam good converting/ripping to mp4 or m4v format on my HP Touchpad.
So most of my previous Handbrake settings won't work with my Galaxy Tab 10.1 (dual core Tegra). I had a lot of files that could play fine in the iPad, other Android tablets, but not on the Tegra. It seems that the poor Tegra has trouble playing high profile HD content, however, even lowering stuff here and there wasn't enough, either the quality would be too low, or it would stutter.
After a couple of days testing I think I've found the perfect one so far, tested with a lot of big bluray rips. Here is it is, from JC Corporation:
Video:A simple how to video showing you step by step how to convert your HD movies and tv shows into a format compatible with the Motorola Xoom, Apple iPad, Samsung Galaxy Tab 10.1, and many other Tegra 2 powered Android 3.0 devices.
Android Xoom Handbrake Profile.
I have no idea what corporation is this, but it worked for me. I tried a lot of profiles from Android forums, lots of conflicting info. This solved my issues transcoding Planet Earth and Rio, Pixar stuff to play in the car for the kids in the back. Very happy with the results, it looks stunning in those gorgeous screens. Once you go tablet, there's no coming back...LOL
Happy to hear what you think, if you have something better let me know. It could still be sharper, I guess, but it's hard to tell. Can't wait for the SuperAmoled Nec Plus Ultra blacks next year...