Well the three easiest solutions to this problem would have been:
1) Pull the drive from the Windows 98 computer and install it inside your Windows XP computer.
2) Buy a cheap 2gb flash drive and copy the files from your Windows 98 computer onto the flash drive and then from the flash drive to your Windowd XP computer.
3) Buy a usb hard drive enclosure. Pull the Hard drive from your Windows 98 computer, put it in the enclosure, then connect it to your Windows XP computer via USB cable.
Also if the two computers are networked you could turn on File and Print sharing on your Windows 98 computer and copy the files to your Windows XP.