First, their driver download site does not have Microsoft® Windows® XP 64-bit version drivers. All drivers are for Windows 2000/XP (32-bit). The RAID driver disk does not have 64-bit drivers..
Second, nVidia’s driver download site has beta Windows XP Professional x64 drivers but they haven’t been touched since 2004 (EditionVersion: 6.25 BETA Release Date: November 19, 2004). The 6.25 RAID disk is missing a file required to install the disk drivers. The 6.23 drivers (released in beta 10 days previous to 6.25) did seem to install correctly. Both drivers come with known issues including: “audio pops and clicks may occur while playing certain games”, “occasional hangs may occur with these drivers”. Judging by the date on those BETA drivers I can assume nVidia has little or no interest in maintaining that driver set (probably because they are concentrating on nForce4 on the AMD Socket 939 instead of the SN85G4’s AMD Socket 754)..
Third, for the RAID drivers you should go to Silicon Image’s web site at IP address 22.214.171.124 (yeah, no domain name)..
Personally, I think this is a shame. The SN85G4 is probably the best looking small form factor PC on the market. Things were a little cramped when the video card was installed but everything else is laid out very well otherwise..
There is a really good thread at Atomic PC called XP x64 – The Essential Collection that was a very good help.