Why not replace the RAID card with the USB card and just use software RAID? If this is a 6 year old machine, its not like you'll be using it for high-performance stuff anyhow, right?

The hardware RAID card adds a failure point, too. If the RAID card goes bad, you'll need another one of the same type to recover the array. That's not the case with software RAID. The only disadvantage is speed, but come on, we're talking about sharing to Windoze PCs here, aren't we? Its still probably going to be faster than the local storage on the Windows machines.

Jim