At this point in time, it's rather pointless for you to go through any "3D tutorials" that talk about 3d collisions, physics, terrain generation, water surface, etc. You are interested in building a 3D game, not a 3D engine. These mechanics are only useful to those who want to make their own engine.

I guess so...

More than anything I just wanted to get a better grounding in certain things, before moving onto the more proper commercial solutions for more practical purposes.

Maybe best would be just to continue to have a look around and read up on some of the theory behind things to satisfy my curiosity, while focusing on the likes of Unity for actual projects for the foreseeable future.

Which right now actually leaves just Unreal Engine 4, since Unity doesn't work on Vista and I BELIEVE (could be wrong) that I saw Unreal Engine 4 does.

EDIT: Actually it looks as though Vista isn't supported... at least it's not mentioned...