Given that I struggled with beta2 and RC1 of the 64-bit versions, eventually giving up after the Vista install trashed the partition table of my array, forcing me to recover everything from backups, the first thing I did was take a backup of all my partitions using Drive Snapshot (for those who care, I used a USB 2.0 external drive that I built from a new drive and an external case that I got "on the cheap" from woot). After verifying the snapshots, I restarted the machine and went into the BIOS setup to rearrange the boot order of my devices.
Finally, with my system looking to boot first from the IDE CD-ROM (dvd, actually), I crossed my fingers and restarted...
Nothing uneventful or even remotely interesting happened through the install, I'm happy to report. The drivers for the nVidia SATA RAID were included in the RTM release, and it immediately "saw" the virtual drive and the pre-existing partitions.
Given the size of the Vista install, I ended up wiping out three primary partitions (0: DOS/System Commander; 1: Windows XP (32GB); 2: Windows XP 64-bit (32GB)) in order to have 64GB to offer Vista.
After a couple of reboots, I was ready to start playing!