I've come across a very useful post from Scalability Experts that talks about how to fully utilise your machine resources for SSIS.
I'm not going to steal their thunder but I'll whet your appetite with the topics covered:
- Max memory available to a package (note this is different to the max available to SSIS as you will read if you click the above link)
- The possible effect of running SQL Server on the same box
- Using Perfmon counters to monitor memory usage
Very interesting and very informative.
-Jamie