Server Can’t Ping LAN PCs & vice versa

I have a Windows 2000 server multihomed w/2 NICs, but on the same subnet. No DHCP setup. No Routing setup. From Server can ping each NIC: 172.16.34.2 & .3 From PCs on LAN can’t ping or find server to logon to domain. Ex. PC IPA: 172.16.34.28. Have a seperate router (172.16.34.200) on LAN for DSL. Def. Gateway det to .200 for server and PC’s. PC’s can ping router and get to DSL. Server can not. Any Thoughts? Help!