Ga. This is where Windows really sucks. It's easy in UNIX.
I've a FORALL utility that I use at work. I just did a search - I'm not sure if the following is the same, but it might help. (Check the FORALL tool)
http://short.stop.home.att.net/freesoft/batch1.htm
If there's a "pure" MS command line method that works, I'd be interested in hearing it. The FOR command seems to have a lot of new options in NT, but I'm not sure any quite do the job.
There's also a new "PowerShell" from MS.