I was having serious performance problems with recorded videos on a 2TB external drive running in a RAID 0 configuration until I discovered that the drive was highly (make that HUGELY) defragmented. I had assumed that Vista defragmenter was automatically defragging that drive, and it was set to do so. But without any kind of drive map or disk analyzer in Vista defragger it's nearly impossible to check the drive for fragmentation or tell if it was defragged at all. Now I'm using the freeware Auslogics defrag to fix the drive -- it looks like it's going to take about a week to finish. I would argue that Vista's "Defrag Lite" is totally inadequate for today's terabyte-sized hard drives.