I am curious to why you would want to process things in serial manner. I would think, in general, that processing things in parallel is better. Better meaning more effienct use of computing resources. You can always process the results in parallel yet still only allow access to the results FIFO. Or in other word you process things in parallel yet make it look like things where processed serially if you have to.
BTW you might be able to get cron to work on your Windows XP system. I have used cygwin's
port of cron successfully on my NT system.