I just completed a week long ordeal to install Vista 64 bit Ultimate on my Mac Pro, and I want to share what I learned with the MacRumors community. There are several things I found that are either not mentioned elsewhere, or are not clearly stated. Note: This is geared towards the Mac Pro, however, other than the hard drive aspect, it applies to other Macs that support 64 bit Vista Only Vista 64 bit can use more than 2GB of RAM on your Mac, which is why I started this project to begin with. I had a 3D image to render with a very large texture. Boot Camp does not support OS X based software RAID. You must use a hardware RAID card if you want to us RAID in Vista. You can partition a drive to install Boot Camp, and there are guides for that - it's pretty easy. However, I think it's easier to use a dedicated SATA drive. I used an old 250GB drive that came with my Mac (the first thing I do when I buy a Mac is upgrade the drives myself). Vista needs room to run, much more so than XP, so plan on using at least a 100GB drive. You don't need to use boot camp at all with this method. A note on Parallels and VM Fusion: I found Fusion to be better, even though I have owned Parallels for a while. Fusion supports both processors and has better support for Direct X, and it's much more Mac-like (easy to use). It also seems faster and supports more RAM. I decided against it, however, because my 3D app ran slow in Fusion (which I suspected). DO NOT buy Vista with SP1. Microsoft decided to use a different boot loader with the SP1 disc and it doesn't work on the Mac. What it comes down to is that it doesn't fully support EFI, which is why I was able to convince Microsoft to send me a disc without SP1 on it. They are not easy to find but it's worth it to spend time; the alternative is ugly - please trust me on that one. DO NOT buy an OEM copy of Windows unless you know what you're doing. I picked up 64 bit Vista Ultimate at Fry's for $199, but when my disc didn't work, I couldn't return it to Frys (it was open) and Microsoft won't send you a replacement because OEM means you have to support it yourself... so I was stuck with a $200 coaster. After traversing a globe of phone trees, I ended up talking to a complaint group Microsoft corporate offices (425) 882-8080, whom were actually quite nice, and sent me an SP1-free DVD overnight. They did so, I believe, because I made my case that the SP1 disc does not support EFI like their documentation states. If you already have, or can only get an SP1 Vista disc, you can use the free Microsoft AIK (Automated Installed Kit) combined with certain DVD burning software. I tried doing this using instructions found here but it didn't work for me after many hours - maybe you can get it to work. It requires the use of a machine with Windows which is not fun if you don't have one already. See this thread MacRumors for more info. It's easier to do the install if you remove your Mac system hard drive before installing Vista. It ensures that you don't format your Mac by accident, and it prevents you from having to hold down the Option key every time it reboots during the install... which means it's basically hands free after you enter the serial #. You can partition the drive and install XP and Vista on the same drive. If you want to do that, install XP first and use the XP disc to do the partitioning. I highly suggest XP SP2 or higher because previous versions are very susceptible to viruses. Once you have Vista installed, you can then install SP1 and all the updates. Then, put your Mac drive(s) back in and use the Option key to choose your Windows drive when booting. NOTE: if you have OS X software raid, be sure to put your drives back IN THE SAME PHYSICAL ORDER. If you don't, you're just asking for trouble. Of course, the best thing to do is to just not use Vista at all - I love to hear about competitors who use Vista. I had no choice because I invested $3,000 in 3D Studio Max many years ago, and I can't bring myself to buy and learn Maya just to avoid this dual-boot nastiness. I personally do not believe in using pirated software, particularly when you are using the software to make money, which I do. I have to admit, I did think about downloading an ISO of Vista from the web without SP1, but in the end I took the high road, and I'm glad I did. As much as I don't like Microsoft (talking to their reps brought back bad memories), it's still stealing. I'm not preaching, that's just my opinion.