Since the i-RAM appears as a normal hard drive, you can install Windows on it just like you would a regular hard drive with no extra drivers (assuming that none are needed for your SATA controller).
A full install of Windows XP Pro can easily fit on a 4GB i-RAM and even on a 2GB i-RAM, but you have to be careful not to install applications into the C:\Program Files directory and disable System Restore for the i-RAM drive among other precautions. Why would you ever want to install your OS on an i-RAM card? We came up with two possibilities:
First off, loading your OS on the i-RAM will reduce boot times.
Boot Time Comparison
Windows Boot Time (Lower is Better)
Gigabyte i-RAM (4GB)
9.12s
Western Digital Raptor (74GB)
14.06s
With a Western Digital Raptor, you can go from the boot menu to the Windows desktop in 14.06 seconds; with the i-RAM, it takes 9.12 seconds. It's not instantaneous, but it's definitely quicker and noticeable.
Our thoughts are that with further optimization, the boot process can be better tuned for very low latency storage devices such as the i-RAM, but that won't happen with any currently shipping version of Windows.
The second reason for installing your OS on an i-RAM card is a bit more specific, but one we came up with when thinking about a secondary benefit of Gigabyte's i-RAM: it's silent.
You could theoretically build a home theater computer using just the i-RAM to hold your OS and map a network drive (hopefully kept in another room) to hold all of your media (e.g. music, movies, pictures, etc.). Paired with a silent PSU and a very quiet running CPU fan (maybe even on a Pentium M based system), you can have a truly silent HTPC, thanks to the i-RAM. You'd ideally want whatever database of your media collection to be stored on the network drive and not your OS, just in case something ever happened causing your i-RAM to lose its data, but it is a viable use for Gigabyte's i-RAM.