Well... I use Illustrator. I own Freehand 10 and looking at Freehand MX looks like it will be a great addition to my arsenal of design tools. Some things you can do in Freehand that can't be done in Illustrator and vice versa, I'd say learn 'em both. It never hurts to have extra skills under your belt. If you're just starting vector design and Flash is your main focus, start off with Freehand MX...