You won't want to set the IP address in the TCP/IP stack bound to the modem to the IP address of the modem, if you don't have a router between the modem and the computer, you should be able to surf to 192.168.100.1 and enter the modem configuration manager. As long as your TCP/IP is set to obtain an IP addres. Assigning the modem IP to the computer really will not help, and will cause you to lose your connection to your ISP.
Banshee76