OK, I've read all the posts on making activesync work across the internet. I'm still in the dark! If anyone has made it work using WM2003 and the X5, pleaselet me know. You can email me off the list if you like.
Check out this form. It has a pretty good step-by-step of what you need to do. Look at the link I posted toward the end of the form. That should get you started, let us know how it goes.