|"I have software thats for designing your own landscaping, it's for windows95/98 disk."|
You could always try to install it on XP (most software for Win95/98 works with XP). If there's any problems, then you'd likely need to upgrade to an "XP-compatible" version of the software.
"Do I have to download the software thats OEM Windows 98, in order to view my landscaping disk?"
If I read that correctly, unless (as mentioned above) it has problems in XP, again, you'd likely need to either upgrade the landscaping software to a version that's works under XP, or run the existing copy on Win95/98. Given that you already have XP on your current machine, it would not be advisable to try to install Win95/98 on a machine that has XP (it would likely damage your XP installation). Find another "older machine" to install Win95/98 onto if necessary.
"Channeling the spirit of jboy..."