What's the best NAS configuration?

On box for best, one box for everyday data

By Stephen Mansfield • In Computer • At 12:16 GMT 17th June 2009

What NAS product or combination of NAS products would best suit the following home network requirements:

RAID 1 storage for important media, eg. photos, home video, etc with minimum capacity of 500GB.
RAID 0 storage for other media and backups, eg. TV recordings, DVD rips, music etc with minimum capacity of 2TB with the capacity for expansion.

The network is a Gigabit Ethernet link across several Windows PCs.

Out of interest what sort of real-world transfer speeds can I expect over 1Gb connection?