I asked the same question in a thread a few months back.
Whatever you do, ditch IDE
From all the input, RAID is the fastest. I'm still not clear what benefits there are of AHCI vs. RAID... from what I understand AHCI supports RAID.
When configured as RAID or ACHI, you can run drives in single or in a RAID array
XP does not provide native support for RAID, so you need to load drivers for RAID. Win7 has native drivers. I think ACHi is supported by XP - can someone confirm this???
Edit: Read this article too: http://www.differencebetween.net/tec...ahci-and-raid/
I think I'm wrong about AHCI allowing discs to be "RAIDed"