To make CoCreate stand out in the noise of the CAD market, you can download Personal Edition for free -- but only until the end of March.
This 3D CAD software is limited to 60 unique parts per assembly, but comes with lots of importers. No add-ons can be used. Also, PE has its own file format incompatible with paid-for CoCreate; the PE files can be translated (unlocked) to CoCreate format when you decide to pay up -- by subscription or otherwise.
After registering, you can download the 85MB worth software from cocreate.com/free . Runs on XP and Windows 2000.
With so many free CAD packages available now, why would you want to try out yet another? The primary difference is that CoCreate is a history-free modeler: it has no history tree that limits editing. So that's a different way to create 3D mechanical drawings, and one that might fit your workflow better.