There’s been a lot of buzz about the Pre-RC1 build of Vista working with Boot Camp. I decided to give it a try, and it was pretty easy. You’ll want to perform a full backup before you try this!!!
  1. First, run the BootCamp Assistant and delete your Windows installation. This will wipe out all your data, but will restore your Mac to a single partition. You only need to do this if you want to perform the next step.
  2. I’m pretty sure Vista won’t run on a FAT32 file system, so you need some way to exchange files between Mac OS X and Windows. I think the best way to do this is to create a third partition. This post (read it all) has lots of details on this. On my MacBook with a 100GB drive, I used this command to shrink my Mac partition and create a 5GB partition for shared data and a 20GB partition for Vista: 
    sudo diskutil resizeVolume disk0s2 72842723328B \
"MS-DOS FAT32" Data 5368709120B  \
"MS-DOS FAT32" Windows 21474836480B
  3. Next, I rebooted, opened a Terminal, and ran this command to create a FAT32 file system on the Data partition (please check the output of diskutil list /dev/disk0 to be sure you are operating on the right partition first or you may wipe out important data!!!): 
    sudo newfs_msdos /dev/disk0s3
  4. Once I finished these steps, I inserted the Vista DVD, and rebooted the Mac. I held down the Option key as it was starting, and selected the Vista DVD as the boot media.
  5. I went through the Vista installer as normal, and all was fine. The only oddity was that when it rebooted, it went into Mac OS X. I opened up System Preferences/Startup Disk and told it to boot from the new Windows partition.
  6. I rebooted and setup continued as normal.
One drawback of this is that Bootcamp Assistant won’t run if you have these three partitions, which make it hard for you to burn new driver CDs. However, you should be able to Control-Click on the BootCamp Assistant app, choose Show Package Contents, and find the driver disk .img file that way. I’m sure there will be other annoyances involved with using a non-standard configuration, so I’m prepared to have to delete these partitions and start anew at least a few more times…