Of course, if you won't be using a lot of soft synths going forward, ignore my comments; but fll Kontackt is a great invenstment for two reasons:
1. It comes with a great sound library.
2. If you have the full player, there are lots of free and cheap libraries. A lot of them can't afford to pay the Kontakt license fee, so you have to have the full player to use them.
NOTE: When you buy full Kontakt you get it's full factory library (Factory LIbrary); however, even the free Kontakt player offers a reasonably good selection of basic sounds (Factory Selection). Unfortunately, I don't see vocals in the free library.