You need to go out to http://premiersupport.dell.com and put in your service tag off of the bottom of your system and download the drivers for your system if you haven't already.  With Widows 98 you need to have the dell power management for pc card modems installed on this system before any modem will work.  Also keep in mind that some modem manufacurers have their own power management software that gets loaded and this would need to be disabled in some cases.  This is assuming that you have a pc card modem and I am assuming this because you said that this card works in your other laptop.......  While you are out on that website make sure you update your bios and any other updates out there you may need.  There are many updates out on that site that you will need to have on your system, especially with windows 98.  Please let me know if you need further information on this to help you update your system.

Thanks much- but now here is my problem: how can I get all of the necessary updates when I cannot connect to the internet with the PC? Will all the updates fit on a floppy?