If the service presents itself as a RAS dialup connection on your PC then you should be able to use one of the personal firewalls, take your pick from:

- Tiny Firewall http://www.tinysoftware.com/
- Zone Alarm http://www.zonelabs.com/
- Black Ice Defender http://www.iss.net/products_services/hsoffice_protection/
_________________________
Remind me to change my signature to something more interesting someday