If your computer is:
CPU 233Mhz
Ram 64Mb
Hdd: 1.5Gb
Then you meet the mimimum requirements. But personally, if my system was in that ballpark, I wouldn't recommend going to XP. My guess is that your system would actually run faster on '98 if it is this old.
The only other consideration is whether or not you have any REALLY old hardware that is not compatible with XP. Not likely, but a possibility. If you are unsure, do a google with your hardware part number and "xp compatible" to see what comes up.
Good luck!