If anyone is still looking for an answer, here is what I did. It's pretty simple, actually.
There are two problems with connecting the linksys router to the 2210, and both are easy to fix.
1. Both the linksys and the 2210 are in the 192.168.1.0 network. it's best if they are in different networks. I was/am using the 192.168.0.0 network on the router. I changed to 192.168.2.0 network like linksys says, but that didn't solve my problem.
2. The second problem is the MTU values don't match. The linksys router has an MTU size of 1500, the 2210 has an mtu size of 1492. I changed the MTU size in the router to match the modem (1492), everything came up.
I had other devices in my network that were already configured for the 192.168.0.0 network ( a print server, some other stuff that needs static IP addresses). Of course, I couldn't reach them with 192.168.2.0 addresses, so I changed my router back to 192.168.0.0 network, and everything works.
Linksys has a very good example on their website, but they don't tell you can use any network except the 192.168.1.0 network. If you are just getting started, it doesn't matter. configure the router exactly like Linksys says, and you should work. Operating system doesn't matter. You are probably using DHCP (Obtain an IP address automatically). If it works with your 2210, it will work with your router.
On the cable modem issue, it depends on the provider. I had Charter cable before I went DSL. I had zero problems. I simply plugged the linksys router (and a netgear router before that) into the cable modem, and they worked just fine. My problems with Charter were not ISP related. I found their tech support staff to be pretty savvy at the time, but don't know now. Their support is now international, and I can't vouch for their knowledge of home networking. On the other hand, I don't know that they can't help you either.