Correct, says right on the top of the product page, XP and newer.
Windows 98 and Windows NT are completely different from each other. XP is NT 5.0 and vista is 6.0 and so on and is based on the nt kernel where Windows 95 and 98 where not. Not to mention the amount of api calls that have been added since then.
But sorry no support for Windows 2000 and older, mainly because of the lack of API calls that the program makes that are only in XP and newer.
Shane