I am in a similar situation to what you have. One phone connection (for caller ID), and one LAN connection. I've connected my one and only LAN connection to my 622, but I've got plans on upgrading to Samsung's BD-UP5000 combo BluRay/HD DVD player which also has a LAN connection (for accessing firmware updates and on-line bonus content). There will be an eventual A/V receiver upgrade in the future as well and I am seeing that many receivers have LAN ports giving them the ability to stream music from networked PCs, or on-line "internet" streams.
I've got an old Netgear 5-port 10/100 switch, which I've connected to the RJ45 on the wall behind my entertainment center. It take care of any and all future LAN enabled devices.
If there comes a day where I outgrow that, I'll go with a 10/100/1000 with a few more ports.
I could easily go wireless, however I've found that time spent on configuring them don't outweigh the added expense. Right now the only WiFi I'm running is dedicated for my notebook and PDA.
Hope this helps.
Spence
P.S. I know I get wordy so the answer is "Yes" a switch would work.