ADSL and NIC problem

I have a machine running Win2K with a 3Com Homeconnect ADSL internal modem doing ATM connection. Whenever I install a NIC the DSL quits working and two new items appear in the Network and dial up connections called ELAN connection 5 and ELAN connection 6, these also show up in the systray and will not go away. When I try to delete or remove them it says I cannot do that, windows may need these to boot. I want to setup the DSL machine as a NAT using ICS but cannot get a NIC installed to work northe DSL if the NIC is in the machine. Any ideas? TIA.