When were your shocks last replaced? They may already need replacement. Don't know for sure, but that spring rate may already be too high for stockers...hold onto the springs until you have money for shock upgrades, is my advice.
My advice would be to do springs/shocks at the same time. Even if your stock shocks are relatively new, it will more than likely still give you a bouncy ride and HURT your handling rather than help it.
I'm on all stock suspension right now and my shocks are worn out. The springs are fine, but it's horrible unless you're on perfectly smooth ground. When cornering, your front wheels will more than likely bounce over bumps - but they won't just bounce once, they'll keep bouncing. As an effect, your steering is going to feel crazy. The car will pretty much understeer because the front wheels are "skipping." When they stop, the front end will snap back to where you are steering making it pretty unpredictable.
Buy the springs if you want to, but wait and install them after you have shocks to go with them.