You're right this is a common topic around here. I suggest you experiment with the Search function (the button is in the golden colored command button strip in the header) and select this forum as the forum of search with model cad as the search term. You'll turn up lots of threads about Model CAD and other CAD's in the results.

Then come back if you need anything more. I'm not trying to sluff you off but it's all been said in so many ways before. Happy hunting.