RAID 0 sounds like a good start, morbo. & comparing audigy 1 & 2, it makes almost no difference. no point spending a lot just to get a little better.
if u are really into so many hard drives, more than 4 in fact, why not IDE card that u can use to plug more IDE devices? chances are some applications may not work on such system. best to have 2 separate power supply units for such venture. 1 PSU for all the hard drives & another for the motherboard. this means u may have to resort to open-case configuration.