I recently purchased a new computer, and I decided to go with the following components:
Motherboard: ASUS P6T LGA 1366 Intel X58 ATX
CPU: INTEL Core i7 920 2.66G quad core with Hyper Threading (4 cores, 8 threads)
RAM: 3x2GB DDR3 1600
Hard Drive: 2x250GB Seagate Barracuda 7200.10 ST3250310AS setup as RAID 1 Mirror
Video Card: MSI N9400GT-MD512H 9400GT RTL with passive cooling design
Case: APEVIA X-ALIEN MX-ALIEN-BK Black Steel ATX Full Tower
The build went fine, but I got stuck trying to install Windows 7 64Bit RC, as I could not get it to load the drivers for either the JMicron JMB363 or Intel ICH10R SATA controllers. The SATA Port 0 and 1 are controlled by the JMicron JMB363 controller, which can be setup as a special Speed or Backup mode using Intel Drive Xpert technology. I couldn't find any information about what these actually were (I assume Raid 0 and Raid 1, but not sure), so I decided to try and setup the drives on the ICH10R controller as a standard RAID 1 array instead. After updating the bios using the built in ASUS EZ Flash 2 feature (very cool!), I setup the ICH10R controller in RAID mode in the BIOS, disabled the quick boot and the Floppy drive (was causing Windows 7 setup to be incredibly slow trying to loading drivers from a floppy drive that didn't exist), and pressed CTRL+i to setup the drives in mirror mode.
Windows 7 setup still couldn't detect any of the drives. The motherboard came with a driver disk, but I couldn't get any of the SATA drivers for Intel or JMicron on it to work. Even after breaking the raid and installing one drive on each controller, and changing from RAID to AHCI, it still couldn't find them. I tried downloading 3 different versions of the ICH10R driver, even the ones that said they were Windows 7 compatible. I final found a driver that worked for the JMicron controller on the motherboard driver disk tucked away in an install directory in an AMD64 directory. This wasn't what I wanted, but at least I was able to get Windows installed. It took a long time and I thought that it stalled on the "Completing Installation" section, but after an hour or so it changed to a message saying that the installation will continue after rebooting (which I force to reboot after 10 minutes of waiting). Looks like they still haven't fixed any of the useless notifications during windows 7 installation.
After Windows loaded up, I downloaded and installed the latest drivers and ran Windows update, which updated the drivers again. A few reboots, and everything looks great, although it still is running off of the JMicron controller and is not in RAID 1 like I wanted. I switched the drives over to the ICH10R controller, but then it wouldn't load into windows. I was about to cry, but then I noticed that there were two drives listed in the boot sequence, and one of them was still a blank drive. I switched the order of the drives so that the one with Windows was on the lowest SATA port, and then after rebooting it loaded into Windows again (crisis adverted!). Now the drives were on the correct controller, which was still setup in RAID mode in the bios. Unfortunately you can't create a RAID array in the boot loader from an existing disk without loosing all of the data, but by downloading and installing the Intel Matrix Storage Console I was able to convert an existing disk to a RAID 1 array. The process failed the first time, but I rebooted, tried again, and after 2 hours (SATA 3.0GB/sec my ass....) I had everything working just how I wanted.
A bit of a pain, but at least I got it to work. It might be that there is a special driver for the ICH10R SATA RAID mode that is hidden somewhere, but I couldn't find anything that worked. Best bet if you are installing Windows 7 64-bit on ASUS-P6T is to connect a drive to Port 0 or 1 and load the JMicron drivers from the install/AMD64 directory. You can then move over to the Intel controller after updating all the drivers in Windows and build whatever type of RAID array you want using the Intel Matrix Storage Console.
Update 10/1/2009: More issues with JMicron controller and IDE drive.