It depends what you are looking for, however Native Instruments Komplete takes some beating for the amount of instruments included, as well as being top quality so is a good place to start, however I recommend you get used to using the supplied VST with Cubase first before adding new ones.

The learning kerb will be steep, but stick at it as you will soon find how limited hardware keyboards are in both quality of sound and features in comparison, however hardware boards have one advantage over pure software based systems, in that they good to go OOTB.

Pop over to the Wersi stand (Booth 5108 Hall B), as it would be nice to get an American view of their instruments.

Enjoy NAMM

Bill