There are several different places to get hardware and fasteners for your SolidWorks projects. The simplest is SolidWorks Toolbox which comes with SolidWorks Professional or Premium. You can also use www.3dcontentcentral.com however it is painfully slow. I recently needed to be able to download bolts and nuts with the thread fully modelled as it had to be printed in 3d with rapid prototyping. After some searching and reading of the SolidWorks Forums, I came across McMaster-Carr http://www.mcmaster.com/
I was delighted to find that I could download the SolidWorks format of every fastener I required with the full history tree intact, and also with the full modelled thread. A big kudos to McMaster-Carr. See below a nice screenshot of a bolt, nut and a square flange mounted bearing with the full history tree.