I already have Windows XP on, but I want to put win 98 as well. How do I do it?

It is difficult to dual boot windows 98 and windows xp when XP was installed first.

It is, however, very easy to do the reverse (install windows 98, then XP). There are several reasons for this, most notably that windows 98 must be installed within the first 8gb of your harddrive, so if you're willing to wipe your harddrive and start from scratch, you will have a much easier time (other wise you will need to do some more painful harrdrive re-organizing with a third party utility like partition magic.

Ideally, you want two partitions, though windows xp will work from the same partition. The problem with this is that you must then install windows xp with fat32, since windows 98 cannot read NTFS (hence, the reason you want to go with two partitions.

Simply install windows 98, pop in your windows xp cd, and when prompted choose ADVANCED NEW INSTALLATION (not upgrade).

Windows XP will set up the dual boot system with a text based menu at bootup that will allow you to choose your OS.

Seriously, though, the best way for you to go is to wipe your drive, create two partitions, install windows 98, then install windows xp on the second partition with NTFS. It will save you a lot of grief.

Thanks, but there's one problem, it's a HP computer, it didn't come with an XP cd, it just has a system recovery partition.

You could try using fdisk and make two hard drives one for xp and one for win89.
so you would have C: for Xp and D: for 98 that should work.