I just bought Belkin's 500VA Regulator Pro™ UPS battery backup (Item #F6C500-USB) with Automatic Voltage Regulation (AVR). This is supposed to protect "against all power disturbances - including brownouts and blackouts." (Also features a USB output which will tell the computer to shutdown when power is interrupted.)
I hope this will help my SCSI -6911 errors. I'll keep you all posted.