If you really after the story and plan understand what the real score on campaign yeah you need SC1, but if not don’t bother other games.
I’m Hands down on SC2 as the best single player and multiplayer p/c game i've played all year.. They've made the multiplayer feel like a MMO in itself, coming closer and closer to earning new achievements and portraits with each game.. I'm hooked.. I cant wait for the zerg chapter to come along; especially the single player which i was pleasantly surprised with, too bad im gonna have to wait for the 3rd chapter of SC2 to sink my teeth into what the protoss have to offer.. I may say all the sacrifices that made by not buying
warcraft gold for a month just to have the SC2 copy are all worth it.