Well, I would install XP. It's a pain finding drivers for '98.
Reformatting with XP is pretty easy, just get a disk, pop it into your CDROM and restart. It should say "press any key to boot from cd"
It will boot, and give you some options:
Click enter on this screen
Then you will press F8 to agree to the terms. Now it will take you to a page that shows your current partitions. Delete the partitions, by pressing "D" and then "L" to confirm. Now type "C" to create a new partition. Once the new partition is made, it will look something like this:
Click enter to install. Now it will ask you what file system to use to format. I always use NTFS. Now it will start formatting, and once it is finished it will copy the files and reboot automatically. This time you don't want to boot from the CD, let it boot from the hard drive. Now it will show the graphical setup, and from there on it's as easy as can be.
Hope this helped!