Another option is to just buy a router. Thats what I would do personally. Less hassle really...plus that way BOTH machines are somewhat "hidden" from the internet. And the xp machine doesnt have to be on for the 98 machine to get online.
There's a belkin router for $10 after rebate from amazon
http://www.amazon.com/exec/obidos/AS...60549-2077654.
Then you just hook the router to the dsl modem...then each machine hooks to the router..usually very simple to get working as you can use most of the defaults.
JP