After that, you'll have to figure out if Windows XP has routing tables that you can configure to allow them to share your DSL connection.
The key thing is to use PPP protocol for the dialup connection, not DHCP.
Back to the null modem idea. If the 2 modems are talking, can't I direct the '98 box to look at the serial connection? In XP, you check "other" when setting up and it gives you the choice of serial conn. Dial up networking is just 1 way to the net. If I could get it to look at a serial port or even a printer port it should work if the 2 boxes are connected with a cable. The modem connection would look like a null modem,....maybe? The problem is I think '98 looks at the serial port and says its got a modem on it or it will look busy with something else. The linux router thingy might be the easiest since I just threw it in a bedroom when I was finished with it. If it would allow dialing in, then we are set to go.