I have never learned how to master Girder and programm my Marantz learning remote (have to do this one day

), so I'm going an easy way: RF controlled trackball mouse sitting on the table next to my right hand.
If you want the easy setup with high WAF (wife acceptance factor), load only the minimum software and use TheterTek player. If you need a custom resolution, load Powerstrip 3 and set this resolution as a video card's default. Set the PS3 to lad automatically and apply the custom res upon startup. Then install the TT player and you are set.
When the HTPC is booted up the PS3 will start and apply resolution settings. Then, when you insert a DVD, the TT player will start automatically. All the features are accessible via the mouse control (well, almost all, but chances are that if you set the TT player correctly, you won't need to use the features that are accessible from the keyboard) and the DVD navigation will be a breeze.
Good luck,
Leszek.