The 2.0 beta is based primarily on feedback received from the 1.5 release, and includes a lot of updates catering to small businesses and homes with multiple PCs. Part of 2.0 includes features for managing a small home network:
Our research has shown that most homes now have approximately 2.5 computers. This means that in addition to securing and maintaining multiple PCs, consumers now need to do the extra work associated with connecting devices and securing networks. To ease this burden, we added to OneCare features such as multi-PC and home network management as well as printer sharing to help address the modern home environment.
Microsoft is a bit of a newcomer into the PC protection market, but they have made great strides to make up for lost time. Some of that included acquiring other companies to remake their products. Some oppose this, particularly personal security companies like Symantec that view Microsoft's attempts at protection as a way of forcing them out.
On the flip side of that, many users have criticized Microsoft for not doing enough to protect Windows users from external threats. The public beta is free, though it does require you to register to access it. You can download it from Microsoft's site.