wow. that's strange that your silverstars lasted for such a short time. i've had the same set in my Xterra for almost 18 months now. when mounting your bulbs, always hold the plastic socket and never the bulb its self. the oils from your fingers stick to the glass and actually cook the bulb when they get hot.

if you were looking for more light for less $$$, try a 9005 bulb conversion. High beam, or 9005's, can be trimmed down to fit a low beam, or 9006, bulb socket. the main difference is that the high beam bulbs are rated at a higher wattage and they aren't capped at the top. with the 9006's, there always seems to be this black cover at the tip of the bulb.

higher watts + more bulb exposure = great results.