I'll list things in what would normally be reverse order, but you'll see why...Operating System
If you want a server OS that simply offers file storage, I'd go with either FreeNAS or OpenFiler. Both support O.S.-based RAID, and their respective implementations are far superior to any RAID implementation offered by either Windows or the on-board ICHx
If you want a server O.S. that offers more than simple file storage, Amahi Home Server
is an excellent choice, and being Linux-based offers all the power of Linux, including software RAID if you wish to configure it. Additionally, as mentioned above, it offers "Greyhole" which is the Linux equivalent of Windows Home Server's Drive Extender.Controller:
Assuming you adopt one of the operating systems outlined above, you can simply attach the drives to the on-board ICHx
R and use it as a "plain Jane" AHCI-enabled SATA controller. This would be the better option for a couple of reasons.
Firstly, parity-based RAID performance on these ICHx
R controllers is woefully inadequate, and gets pasted by O.S.-level RAID implementations (except the Windows one, which is just as bad). Secondly, for a stable RAID 5 array, ICHx
R needs drives which support TLER, otherwise it can end up dropping them out of the RAID set, which in turn will cause more problems.Drives:
Western Digital's Caviar Green drives will no longer enable TLER, so you'll have to buy their much more expensive RAID Edition drives. The Samsung F4EG drives support TLER but it will not survive a power cycle, so it must be enabled on every reboot. Additionally, you MUST flash the Samsungs with the latest firmware - the risk of fatal data loss is too great. Hitachi's 7K2000 drives behave well in RAID but are 7200RPM - not necessary for storage drives. Seagate's Barracuda LP series I cannot speak for - perhaps someone here can give an insight?
So, to summarise, my advice to you is: a)
choose an O.S. which supports software RAID or redundant storage pooling, then b)
use the on-board ICHxR as a normal SATA controller and finally c)
pick normal desktop-class drives and save yourself some cash.