I have to acknowledge that having just "AHCI" on the driver name will lead to confusion on using this for a system set on RAID mode, being honest this happened to me too until I checked the release notes 
Now, I have to admit that i'm also surprised that IRST 10.1 is listed for Microsoft* Windows* 7 under the DX58SO's downloads. To my knowledge, Win7 support started from 11.6 and that is something you can see by checking IRST 11.2 release notes.
However, I know that 11.2 is confirmed as stable in Windows* XP and Windows* 7. So you may go ahead and use that version or use the different versions, 12.5 and 10.x in XP, that should not represent a problem.