Two DLink wireless cards. One pci in a desktop the other pcmcia in a laptop

Desktop: xp
Laptop: 98

The desktop connects to the internet through router.
When I try and set the wireless connection to allow others to connect through it, it demands to be 192.168.0.1 which doesn't really fit into my network plans aka that addy is taken.

Any idea how to setup these to cards to work in ad hoc in such a way that the laptop can get on the internet through the desktop?

Thanks