Windows 2000 RIS using Cisco 2900 Switch

I wonder if anyone can help, I have used Microsoft’s RIS to distribute images using a plain 10mbit hub successfully. I now want to use one of Cisco’s nice 10/100mbit Catalyst 2900 switches to take over for quicker deployment but the client machines can’t even connect. I’m assuming Bootp isn’t working as it shows a message saying “DHCP Server could not be found” or words to that effect. The switch is straight out of the box with no mods. Does anyone have any ideas on getting this working? Do I need to do any configuring for the switch?

Thanks in advance for any help.