I am having trouble connecting

I am having trouble connecting my tivo and computer/internet up through my router, also with a motorola modem - I'd prefer it to be wireless so I can use my laptop. When I connect up the router (linksys G 2.4 ghz..old one, I know) the internet does not connect. As soon as I take the router out of the picture, the internet works. But I think the router works because when it is connected I am able to access the linksys setup page. If the router is not used, I cannot utilize my Tivo. I switched from internet via telephone line to cable last week, and noticed I hadn't had a programming download on tivo since the switch, I went in to the tivo settings to change my network settings, powered off some cords to move them, and when I powered then back up, the router doesn't work properly anymore. Any ideas?