Omar Shahine has a nice entry detailing how to configure the Motorola voice modem you get from Vonage to work in conjunction with your home network router. By placing the Vonage voice device first in the chain on your network (directly connected to the Internet) and the router behind it, you can take full advantage of the QOS (Quality Of Service) capabilities of the voice device, which helps ensure other network traffic from your LAN doesn't suck up all the bandwidth and kill your voice call quality.

I did a similar thing on my home network a little while back (different equipment, same basic procedure), and found that it substantially improved my voice call quality when computers are hooked to the LAN, especially since my computers often do automated/scheduled things that will - if left unchecked - hog the pipe from time to time.

UPDATE/SHAMELESS-PLUG:

I just noticed - if you want to sign up for Vonage service, they have a referral program where I can send you an invitation and you'll get the first month free, and I'll get an equal service credit - which is good for everyone! Just email me here:  and I will send you the invite - be sure to send your name and the email address you want the invite to go to.