Connecting to router but not Internet

Greetings all.

I am having some issues getting our network in our office working. We have 2 computers connected to the router directly, 1 on Wifi, and 3 others connected through a switch in a different room.

The two computers directly connected and the WiFi computer connect without any additional setup perfectly fine. The 3 that connect through the switch however do not get an IP automatically assigned, it seems like for whatever reason the DHCP server is not communicating with them.

If I manually input the IP settings for those 3, assign them an IP, gateway etc, they connect to the router and networked printers fine, but do not get an internet connection. I have tried dns flush and ipconfig release/renew with no luck. Any ideas? I'm stuck here and any help would be tremendously appreciated. The 3 computers having the issue are running windows XP. The router is a Motorola Netopia 3000 and I am on AT&T DSL.

My first guess would be that the wire going from the wall to the switch isn't connecting back to anything on the other end.

What kind of switch is it? Have you tried looking at it's configuration or is it fairly "dumb" and has no configuration?