Is it worth installing a second 8800 GTX in SLI mode for vista? I have really found a definitive answer for this. Also how much power would I need. I have a Q6700, 2 HDD, 2x DVD/RW, 2x2GB Ram on a 600 watt PSU. If this isn't enough power show I just get a new PSU or install a dedicated VGA PSU like the Thermaltake Purepower 250w PSU in my 5.25" bay? Thanks. Dave