2 940's (2.8ghz) Vrs 1: G34 @2Ghz?

I have a ? that, perhaps will sound like a "Duh",
but im not sure... so im asking.

This computer is for an AUDIO workstation.
(DAW)

Primary Audio software is: Cakewalk Sonar
(Optimized for multicore)

Right now I have a system running:
2 (Dual core) opteron 940's (2.8ghz)
-4 cores @ 2.8ghz-
Tyan Mobo
windows XP 64 Bit Pro
WD Raptor 10,000 RPM :C drive
12GB Ram

I was REAL disappointed W/ this system.
I know SOME Soundcard Latency is to be expected,
but I *want* it to be so "seamless" (esp for Vocals!)
its as if each plug in, was an "outboard unit" in a rack.
Please, feel free to point out if the below build,
can not meet this expectation either.

Im thinking about moving to:
Dual Socket Asus Mobo
But @ the moment can only afford
ONE: G34: 8 core @2Ghz CPU
(Would run Windows 7, and 4Gb ram at first, more added later)

The questions I have:
I know the Xtra cores and 12mb L3 Cache will have an impact,
BUT!
Am I going to see is a SICK performance increase?

IE: Great enough to justify spending so much money,
Ill have to eat rice, and strawberry smoothies for 9 weeks?

if I would NOT see that great of a boost,
If I install a new SSD HD in the Dual core 940 opteron system,
and upgrade to Windows 7 how much of an impact would that have,
on running real time FX, and mix down times?

Ive seen people frolic around, (like Bambi!) raving,
about performance gains of new SSD's + Win 7 installed,
Sure I know they are faster, but I wonder how much is that new joy expressed,
ts the result of a clean install of windows,
rather then the hardware if ya know what im sayin?
(IE; Person had XP/Vista w/ Registry errors all over, so system was slow?)

Also, if anyone knows of the THE MOST reliable SSD hard drives,
please mention them. Ive heard/read a LOT of SCARY things about SSD's.
Im pondering a Samsung 470 as a C: drive,
then adding more later as drives that hold sound library's.


THANX SOOOOO MUCH for all thoughts!