in regard to a raid5 setup, i notice that Adaptec has a raid controller card that has 8 connectors. would this be any faster than a 4hd setup. there would definitely be a greater volume of space but, is there a rule of diminishing gains in speed ?
RAID 5 gives you large capacity with some redundancy, in case a single drive fails. However, its performance is lower than a simple striped pair. However, editing either DV or HDV can be satisfied without using RAID. You only need a RAID when you are editing higher bitrate video, like true HD, which is best managed using an external RAID with its own controller processor like the G-Tech products.
You also have to be careful selecting your drive sizes, as Windows XP can only address 2 TB for any drive set. With Vista, you can address larger drive sizes.