The cheaper V-brake arms have quite a bit of flex in them that really kills your stopping power. I upgraded from OEM Tektros to Avid SD 7's and it's absolutely amazing the difference. Also, tightening is NOT the answer when trying to adjust v-brakes. It's best to LOOSEN the side that's touching rather than tighten the side that isn't. All the springs do is hold the pad off the rim when you aren't braking. Your finger strength is what is applied to the rims. So why tighen a spring that has an exclusive purpose of working AGAINST your braking efforts?

Oh, and +1 on the new pads. If that doesn't cut it then cruise eBay for a decent set of V-brakes..