(you did check the IP addresses, didn't you?).Yes I did, using ipconfig from a dos window. Ipconfig returned three sets of addresses, the DVB card with correct ip address, my network card with correct address, and another one with all details 0 (ip address 0-0-0-0 etc).
I am assuming that the third one is part of the leftover config from when I had the card in a different slot. Does this sound like a reasonable assumption? Unless I can think of a more creative solution today, I am planning to format the drive and start from scratch with Win98 again tomorrow. Hopefully that'll fix it!