problems with DHCP and Samba

Hi! I started to use Suse 9.0 a few weeks ago. I try to build up a simple network in my office with Suse as the file server (with Samba) and WinXP clients. For the first time, I used my Ericsson ADSL modem/router, which is also an DHCP/DNS server and the whole network was working. Then I tried to use the network without the ADSL modem/router, but I was not able to reach the network at all. I tried to set up the DHCP server in Suse, I did it, and it seemed to be working, but I still was not able to reach the network. I was thinking about setting up the named server, but I am not sure, if it was the reason of the problem or not. The network is still not working... Where could I find some solution? Best regards: KI