Running Miltiple Instances of 1 Program Simultaneously

Hi,

I'm not quite a Vista user yet, not until I get the new computer I
built to take less than 10 minutes to boot, but when I do get it
working, here's what I want to do:

I have a program, Nikon Capture NX2, that only allows 1 instance of it
to run at a time. When I have maybe 300 - 400 pix to process in batch
mode, to, say convert them from the proprietary *.NEF (raw) files to
compressed "*.jpg" files that all other apps can work with, I want to
be able to start this program multiple times and assign each one to
its own virtual core in my Intel i7 computer.

The question is, then, how? Is there a way to log in to 8 different
user accounts and set up batch jobs in each with a set, say, 50
pictures out of the 400, to effect simultaneous processing? Is there
a trick in Vista to allow me to open my software multiple times in the
same user account?

Of course, I'm looking to reduce the execution time, and maxed out my
DX58SO motherboard with 6 Gb of memory, and bought the 3.2 Ghz version
of the i7 processor, and this software is really the main need for
speed - if it won't work that way, then I'll look at using the WINE
utility under UBUNTU to attempt the same thing in with Capture NX2.

Thanks in advace,

Dave Head