That’s really difficult to answer. As far as software is concerned, there’s many different packages out there and really it’s best to just use whichever your employer or school uses. Plus, they can be very expensive without a student license. At my uni, we use Solidworks and AutoCAD for most things and I can get them all for free through the university. There really isn’t a best package but I think you can register as a student on Autodesk’s website and then get access to a lot of software for free so that might be worth a try.
And then for hardware, I have an i5 Win7 laptop with integrated graphics that gets by pretty well. A lot of my course mates use Macs and Boot Camp Windows for their CAD software.