I have Nuclear Glory and it is awesome. Built in gravity and ray casting commands along with excellent collision for .x, .3ds, and ,.dbo models (may be others but this is all I have used). So you can use Nuclear Glory for your models along with using DBP's matix commands and have a fairly simple to use collision & gravity/jumping system. Add the ray casting feature to it and you have the best deal on the planet for $15.
"People don't fail ..... they stop trying." Specs. P4 2.8GHz 800 FSB | 512MB DDR333
GeForce FX 5200 AGP 256MB | Windows XP Pro Full