threads vs. processes

After following a lot of the email discussions, I thought I'd test out
and see the performance benefits of using ithreads.
Yeah, I was apprehensive and kind of expecting the results below.. :)

I am using perl 5.8.6 on Linux 2.4.18-14

Results from a test run that in which each thread/process is simply
looping and doing an 'ls' on the local filesystem.
I used Proc::ProcessTable to gather the system memory statistics.

With 50 threads:
    Total memory used = 365797376 
    Percent memory (pctmem) = 24
With 50 processes:
    Total memory usage = 513978368
    Percent memory (pctmem) = 32

So, really they are comparable and I'd expect threads to use more
memory as the number increases.. I couldn't really get 100 threads to
run for me successfully yet...

Anyone else have similar numbers that we could compare with? 
-Ram