Windows XP: I would like to auto synchronize files between a a local drive and a network drive.

I am aware of Windows Briefcase but it is very slow and I have to tell it to synchronize. I really like the way Dropbox does there synchronization as it is almost instantaneous. It is very impressive. I would just use Dropbox but I cannot install it on the remote machine. Is there some tool or script I can create that will watch a particular folder for any changes and then sync those changes to the networked drive automatically and nearly instantaneously?

CLARIFICATION:

I would like this tool/script to to be a daemon that starts when windows starts and continually monitors a folder for any changes to its contents. Once it observes changes in the source or the destination it synchronizes the files that changed (Very similar to the way Dropbox works). I have a good idea about how I would do this in a Perl script and if a tool does not exist that does this I will write it myself in Perl. If someone has already done this can they share the script?