Like @ said, Inkscape is a good vectoring program. And I'm telling you, it's EXTREMELY good for a free program. At least I don't feel the need for Adobe Illustrator or anything else, when you have Inkscape. It has everything you need, you just need to spend some time with it to learn how to use all the tools and features.
Just take a look at the vectors I've made.
I'm still rather new to vectoring but as you can see, I can make quite decent ones with patience.