Upgrading from Win 98SE to XP Pro

Has anyone upgraded their Win 98SE to XP Pro? How did it go? Any lessons learned? Are the Win 98SE Operating System files still hanging around after upgrade to XP Pro? Did any applications/software previously installed on 98 need to be reinstalled to work on XP? I looked on MS XP web page, they made the upgrade seem simple, is it as painless as they say? Any advice would be appreciated…