windows multibooting problem,help!!!!!!

i have install XP professional in my desktop and my system partition is NFTS,the other is FAT32.now i have to install another os win98,but microsoft support say it is impossible.they told me i have to uninstall XP and then install 98 first,then install XP.but by doing so,i will not only waste more time but also risk losing my important application and data.
can you help me? it is very important, hope you will help.thanks!!!!!!!