well I understand getting the runaround and having the ISP try and get you to buy "their" stuff, but the only way to be sure you get a compatible modem is to go through the ISP.

If you do not want to talk to the ISP, usually most ISP have a website that has faq's and troubleshooting guides tell you what type of modem you may need. But if I ma not mistaken most, if not all, modems should work. Just make sure you get a dsl modem if you have dsl and cable modem if you have cable internet.

as for a router, that depends on what you do with your computer. If you use bittorrent a lot and also game a lot, then you would want something with very good Simultaneous Throughput. this way the router does not crash because it can not handle all of the packets being sent.