I have had very good results with the Netgear
SC101. I comes empty and uses 1 or 2 IDE hard disks (note, it cannot read FAT or NTFS so it reformats them and whatever is on there is lost.) In 2 drive mode it can be used as a mirror or each one alone. It connects via your LAN (10/100.) It supports TCP/IP, DHCP, and SAN. At $90 (retail) and $60 at Staples (ok, $59.50) it is a low cost alternative.
I keep on-site backups on it as well as storage of ebooks (I wonder if they will ever catch on?

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It has been in use since November 2005 and I have no unresolved complaints. (There were some driver issues at the start but they were quickly resolved by Netgear and never resulted in any data loss, just slow transfer speeds and the driver unloading itself. Both have been fixed.)