Questions about the 4D/120SX

[Steve Scot Roy]

We are considering buying a 4D/120SX with 4 processors as a compute
server here and I would like to know if anyone out there has more
information about them.

How well do these things parallelize?  There were some postings a while
ago with one person claiming 75% ( factor of 3 speedup with 4
processors) and another claiming that his parallelizer had bugs.  
How code dependant is the speedup? 
These things claim to be -executable- compatible with single processor
machines, how is this done?  If you use the parallelizing optimizer on
it and then run it on a single processor machine, does it work?
Can you tell each processor to run
independantly for so each of many users sees a single processor?
Do all languages parallelize?  Specificly, does C parallelize?

How much better is the 2XX series than the 1XX series?  What is the
difference?  What speed do people -really- see on these beasts?

How much memory do these things need?  Some postings said they were
useless with 8Meg, another was complaining at 16Meg; how much is enough
and how much does it cost?

In general, how stable and bug free are these things?  Will I wonder
every time a program isn't working whether it is my fault or its?

Thanks a lot in advance.

Steve Roy
ssr at acm.princeton.edu