If you use a free service like DYNDNS.ORG and run a DYNDNS client on your MAC PRO you can access your MAC PRO remotely via a constant URL.
Just open the right ports in your router, and on your MAC PRO and share your MAC PRO drives and you have direct access for file sharing or screen sharing etc.
If you have an Apple router and use MobilME you can share that way instead of DYNDNS.
There is also a wonder (if expensive) program called RUMPUS that will turn your Mac Pro into a server with http and ftp access.
Thanks, I'm trying to update the firmware on the router now, Cisco WRT160v2, but the damn thing is stuck at 98%. I cancelled that before and now it wont let me commit any changes I make, such as opening ports.