Rediculous!
I believe win98 needs to be on the first 2gb of the disk, so that needs to be your first partition.
You can move you XP partition over using Partition Magic.
However, XP will become unbootable once you do this.
So here's the steps. I was able to install 98, XP and Linux on my laptop with XP installed first by doing this.
First, install XOSL boot loader, (by far the prettiest and best bootloader)
http://www2.arnes.si/~fkomar/xosl.org/
Then, use partition magic or something similar to shrink and move your XP partition over. Create a fat32 partition as the first partition for win98. Be warned you won't see your XP partition in 98 if it's formatted as NTFS unless you have some kinda hack for 98. So I would recommend using a fat32 partition for xp. But you can't convert it from ntfs to fat32 as XP won't boot (at least, with my experiance).
Now, with xp on your second partition, install 98 on your first.
Reboot and setup xosl to see you 98 partition. And now you can boot both
Yarr join teh New and Improved LoGD!