Our Setup: XP 64-bit or Vista 64-bit?

Question

Let me break down the situation here:
A year ago we built a computer from scratch. I'll list some of the basic specs here:
A nice Tyan motherboard (can't remember the model)
4 GB of RAM (4 x 1 GB sticks)
an nVidia GeForce 8800 GTX video card
TWO Dual-Core AMD Opteron 270 (2.0 GHz) - [dualcore + dualprocessor]
10k Raptor hard drive for operating system
3x500GB RAID as "video" hard drive
Adobe Premiere Pro CS3
Now, after building this computer over a year ago, Windows Vista had JUST been released, so we weren't interested in installing Vista yet, due to not knowing how great it would be. So with this awesome computer, we ended up just installing regular 32-bit ole' Windows XP on it.
Now it's been a year, and the computer is in need of a good format. We're trying to decide which operating system to install now. Obviously, XP32 is the SAFEST choice, but probably the slowest, considering we have dual-core dual-processor here and 4GB of RAM, and want to take advantage of all of this.
So I guess we're kind of wondering what to expect if we go to XP64 or Vista64. Which is going to give us better performance? This computer is basically ONLY for video editing, not much else. Literally installing Adobe's software, and maybe small needed things like Nero and whatnot. I haven't really heard too much about XP64, and a lot of the stuff I hear about Vista is conflicted. AND also keep in mind that next month, XP will be upgrading to SP3 and Vista will be upgrading to SP1, and VistaSP1 sounds quite promising.
All of the hardware and software we have apparently has Vista drivers (I've checked online), so there should be no concern here.
So it's simple. We're on XP32 at the moment. Should we go up to XP64 or Vista64, and if so, and which one and why?

Answer 1

Adobe Dynamic Link "Import After Effects comp" fails in Vista Business 64 bit
I am posting this, since in my search, I found no other reference to this problem on the web. If someone has a fix then great. Should someone have the same issue, it may confirm a glitch running CS3 Production Premium in Vista 64 bit. I run XP 64 bit and Vista 64 bit on a dual boot (same hardware) so it was easy for me to troubleshoot the " serious error" Premier gave me when I tried to import an After Effects comp through Dynamic link in Premier Pro. Below is the scenario.
1. The following sequence for Adobe Dynamic Link>New After Effects Composition works fine in both Win XP Pro 64 bit and Vista Business 64 bit :
I open After Effects CS3 to an untitled composition then leave AFX running in the background. Next I Open Premier Pro CS3 to create a new project in the following format:
Standard NTSC video (4:3 interlaced). 48kHz (16 bit) audio.
Editing mode: DV NTSC
Timebase: 29.97 fps
Video Settings
Frame size: 720h 480v (0.900)
Frame rate: 29.97 frames/second
Pixel Aspect Ratio: D1/DV NTSC (0.9)
Fields: Lower Field First
In Premier Pro CS3 I choose File> Adobe Dynamic Link>New After Effects Composition. My project window now has a 11 sec dynamic link linked comp 0 movie file which is black video. I return to After Effects and find a new comp named "dynamic link Linked Comp". I import a Microsoft DV 720 X 480 48.000kHz/16 bit stereo 30 sec video into the AFX Project window then drag it to the timeline. I return to Premier Pro and find the 30 sec movie in the Premier timeline. I am able to make changes to the movie in AFX and they reflect in the Premier timeline.
2. The next sequence for Adobe Dynamic Link>Import After Effects fails running on my Vista Business 64 bit OS. It works perfectly running on Win XP Pro 64 bit.
I open After Effects, import an NTSC Microsoft DV 720 X 480 48.000kHz/16 bit stereo 30 sec video, drag video into the "create a new comp button" at the bottom of the project file then save the comp. I open a new Standard NTSC video (4:3 interlaced) project in Premier Pro CS3 then choose File>Adobe Dynamic Link>Import After Effects Composition. I get an Adobe Premier Alert " Sorry, a serious error has occurred that requires Adobe Premier Pro to shut down. We will attempt to save your current project." I click OK and Premier closes.
System: Dual boot Win XP Pro 64 bit and Vista Business 64bit, 3.2 GHz Pentium D 940 Dual core, Asus P5WD2 Premium motherboard, 8 gig Crucial DDR-2 667 ram, WD 5000AAKS and WD 7500AAKS SATA hard drives, Dual Asus EAX300 Video cards.
The above comparisons were done on a fresh load of both OS's with the latest drivers and the only programs I had installed were Microsoft Office 2003 Pro, Quicktime, Firefox and Acrobat. I have all the latest CS3 updates for Production Premium and the latest Windows updates.