Setup a Belkin F7D1301 router with a Sagemcom Fast 1704 Modem/router

Really need some help here, going crazy . We have a Sagemcom FAST 1704 modem/router from windstream, our ISP, and have been trying to get servers going for Minecraft game with no luck. So we thought that we could attach our Belkin router to the modem since we were having port forwarding problems. I have tried numerous times to set up the router with this modem and have even tried the bridge mode, but then I don't get internet access through the Belkin router....have no idea what I am doing wrong . I am running Windows XP....and my brother, who I want on the same network, is running Windows Vista...which I really hate. I had my XP connected, but could not get the Vista connected....then I completely messed it up and just am at my wits end....can someone please walk me through this? Let me know any info you need and how to send it to you .
Thanks a lot,
Deb