Can anyone help me understand which CPU I need?

Thanks for any help in choosing the fastest solution for our needs; I
need to buy a couple new workstations. I'm confused between the A64,
Conroe, Woodcrest, and Socket F Opterons.

We currently run dual 248 Opteron and single Xeon workstations with 4
or 6 gigs of RAM. We run Matlab to crunch ~2 gig data files. Some of
our jobs (mostly DSP and statistical analysis) take hours.

Matlab is single threaded, so can not itself take advantage of more
than one processor (though I don't know how much Matlab is helped if
there is a second processor to do other things). Generally, we have 4 -
6 gigs of RAM, and use it all for the single running Matlab. We have 12
gigs of swap. We run Suse Linux. We try to avoid using swap. Our Matlab
script (EEGLAB) generally loads all of our data file into RAM, it seems
but in generating secondary results may go into swap if we are not
careful.

Thanks in adance...

JK