Intel Rapid Storage Technology for DX58SO - Version 10 or 9?

I've got a DX58SO, and I've updated drives based on the Intel download page:

http://downloadcenter.intel.com/SearchResult.aspx?lang=eng&ProductFamily=Desktop+Boards&ProductLine=Intel%C2%AE+5+Series+Chipset+Boards&ProductProduct=Intel%C2%AE+Desktop+Board+DX58SO&OSVersion=Windows+Vista+32*

The latest Intel Rapid Storage Technology utility displayed in this selection is version 9.6.0.1014, dated 3/19/2010. So that's what I'm running (under Windows 7, 64-bit).

However, perusing the Intel download center, I find a page for a newer IRST 10.1.0.1008, dated 12/15/2010:

http://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=2101&DwnldID=19607&lang=eng&iid=dc_rss

Why doesn't this show up in the DX58SO list? It shows up in the more generic X58 page:

http://downloadcenter.intel.com/SearchResult.aspx?lang=eng&ProductFamily=Chipsets&ProductLine=Desktop+Chipsets&ProductProduct=Intel%C2%AE+X58+Express+Chipset