32 to 64?

I know this topic has probably been driven into the ground as I read extensively here and other sites... but I still am uncertain about what to do since there seem to be a few inconsistencies in what I've read that I would like to get cleared up before I make that leap... 
 
I have Sonar 6 SE running on Windows XP Pro and am looking to upgrade to Vista Ultimate 64-it to access more memory. (I have 8GB of PC2 8500 available) I've been reading on here and everywhere else I can think of to find a definite answer and am still uncertain. I work completely on software synths including Reason 4.0 and Omnisphere which are both pretty RAM hungry. 3GB gets used up mainly in my huge projects which use a combination of Reason, Philharmonik (more than one instance at times) and Omnisphere...
 
I read in the below article that Sonar can run 32-bit VSTs on a 64-bit OS... is this true? What are the requirements? Can you do 32 bit Sonar on a 64-bit OS, or does it have to all be 64? Will 8GB give that much of an advantage on 64 considering it runs a little more RAM heavy... (or does it?) This a sample of some of the conflicting info I've read... (not necessarily here)
 
Here are a few of my VSTs... (don't want to lose any of them)
 
MusicLab Realguitar 2L, Reason 4.0, Garritan Personal Orchestra, IK Multimedia Miroslav Philharmonik, Spectrasonics Omnisphere, Steinberg Virtual Guitarist, Roland Groove Synth....
 
http://createdigitalmusic.com/2010/08/04/the-most-out-of-windows-7-choosing-and-optimizing-windows-for-music/#more-12534
 
I know this is a lot, but just wanting to get some advice from those of you who may have already taken the leap... If I'm going to have to sacrifice my VSTs then I'll just suffer with 3GB and/or work my projects a little more efficiently I suppose... Thanks in advance for any assistance...

I don't think you'll get the RAM benfits of going x64 if you stay with SONAR 6SE.

The small performance increase you might get is not worth the expense of buying the OS, let alone the work of installing all your software again. You also need to use the Windows 7 compatability(wrong term) tool which will tell you if your system will even run Win 7 x64

If your machine was a little more modern and you were running SONAR 8.5 then yes you'd get all the benefits