Ok, I think this should not be too difficult, but you have two options the easy way and the hard way. I'll run through the hard way first.
You'll want to have 2 network cards in your Win2K machine and 1 network care in the 98 machine. Connect one NIC on the Win2K machine into a hub with the 98 machine. Connect your other NIC in the Win2K machine to your cable modem. Run Internet Connection Sharing on the Win2K machine. It has been a while since I've run it, but if I remember, it will create a disk to automatically setup the client machine (98) to use the shared connection.
The easier way would be to buy a DSL/Cable modem router. This would be ideal if you have 2 nics and no hub. Go to Amazon.com and put a <a href="http://www.amazon.com/exec/obidos/ASIN/B00005IBYY/slickdeals/107-3965615-6181339">SMC 4 port DSL router w/print server</a> in your cart. Then during the checkout process enter either AMZNAMEXBMVD ($15 off $100 purchase) or AMZNDSVRCARD ($10 off $70). Once you purchase the item, print out and mail-in this <a href="http://images.amazon.com/images/P/B00005IBYY.01.RB01.LZZZZZZZ.gif">$20 rebate</a>.
The advantage to the router is that you can access the net without having to have a "server" PC on all the time. The connection sharing is preferrable if you are going to have the Win2K machine on all the time and you already have the hardware.
--So says Polychronopolis..